Kubernetes Mesos integration

This commit includes the fundamental components of the Kubernetes Mesos
integration:

* Kubernetes-Mesos scheduler
* Kubernetes-Mesos executor
* Supporting libs

Dependencies and upstream changes are included in a separate commit for easy
review.

After this initial upstream, there'll be two PRs following.

* km (hypercube) and k8sm-controller-manager #9265
* Static pods support #9077

Fixes applied:

- Precise metrics subsystems definitions
  -  mesosphere/kubernetes-mesos#331
  - https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion_r31875232
  - https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion_r31875240
- Improve comments and add clarifications
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875208
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875226
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875227
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875228
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875239
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875243
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875234
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875256
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875255
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875251
- Clarify which Schedule function is actually called
  - Fixes https://github.com/GoogleCloudPlatform/kubernetes/pull/8882#discussion-diff-31875246

contrib/mesos/pkg/queue/interface.go

@@ -0,0 +1,103 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package queue
+
+import (
+	"time"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/cache"
+)
+
+type EventType int
+
+const (
+	ADD_EVENT EventType = 1 << iota
+	UPDATE_EVENT
+	DELETE_EVENT
+	POP_EVENT
+)
+
+type Entry interface {
+	Copyable
+	Value() UniqueCopyable
+	// types is a logically OR'd combination of EventType, e.g. ADD_EVENT|UPDATE_EVENT
+	Is(types EventType) bool
+}
+
+type Copyable interface {
+	// return an independent copy (deep clone) of the current object
+	Copy() Copyable
+}
+
+type UniqueID interface {
+	GetUID() string
+}
+
+type UniqueCopyable interface {
+	Copyable
+	UniqueID
+}
+
+type FIFO interface {
+	cache.Store
+
+	// Pop waits until an item is ready and returns it. If multiple items are
+	// ready, they are returned in the order in which they were added/updated.
+	// The item is removed from the queue (and the store) before it is returned,
+	// so if you don't succesfully process it, you need to add it back with Add().
+	Pop() interface{}
+
+	// Await attempts to Pop within the given interval; upon success the non-nil
+	// item is returned, otherwise nil
+	Await(timeout time.Duration) interface{}
+
+	// Is there an entry for the id that matches the event mask?
+	Poll(id string, types EventType) bool
+}
+
+type Delayed interface {
+	// return the remaining delay; a non-positive value indicates no delay
+	GetDelay() time.Duration
+}
+
+type Deadlined interface {
+	// when ok, returns the time when this object should be activated/executed/evaluated
+	Deadline() (deadline time.Time, ok bool)
+}
+
+// No objects are ever expected to be sent over this channel. References to BreakChan
+// instances may be nil (always blocking). Signalling over this channel is performed by
+// closing the channel. As such there can only ever be a single signal sent over the
+// lifetime of the channel.
+type BreakChan <-chan struct{}
+
+// an optional interface to be implemented by Delayed objects; returning a nil
+// channel from Breaker() results in waiting the full delay duration
+type Breakout interface {
+	// return a channel that signals early departure from a blocking delay
+	Breaker() BreakChan
+}
+
+type UniqueDelayed interface {
+	UniqueID
+	Delayed
+}
+
+type UniqueDeadlined interface {
+	UniqueID
+	Deadlined
+}