Add timeouts to HealthChecks and retry checks

Fixes issue #3532. Added timeouts for HTTP and TCP checks
and enabled kubelet/probe to kubelet#maxRetries times
before declaring Failure.

Added Probe.TimeoutSecs to API

Probe variants now check container.LivenessProbe.TimeoutSeconds
Also added a test for timeouts in http_test.go.

pkg/api/types.go

@@ -279,6 +279,8 @@ type Probe struct {
 	Handler `json:",inline"`
 	// Length of time before health checking is activated.  In seconds.
 	InitialDelaySeconds int64 `json:"initialDelaySeconds,omitempty"`
+	// Length of time before health checking times out.  In seconds.
+	TimeoutSeconds int64 `json:"timeoutSeconds,omitempty"`
 }
 
 // PullPolicy describes a policy for if/when to pull a container image