Rework hack/ and build/ directories.

* Rewrite a bunch of the hack/ directory with modular reusable bash libraries.
* Have 'build/*' build on 'hack/*'.  The stuff in build now just runs hack/* in a docker container.
* Use a docker data container to enable faster incremental builds.
* Standardize output to _output/{local,dockerized}/bin/OS/ARCH/*.  This regularized placement makes cross compilation work.
* Move travis specific scripts under hack/travis

With new dockerized incremental builds, I can do a no-op `make quick-release` in ~30s.  This is a significant improvement.

.travis.yml

@@ -6,17 +6,17 @@ go:
 
 install:
   - go get code.google.com/p/go.tools/cmd/cover
-  - ./hack/install-etcd.sh
+  - ./hack/travis/install-etcd.sh
   - ./hack/verify-gofmt.sh
   - ./hack/verify-boilerplate.sh
-  - ./hack/install-std-race.sh
+  - ./hack/travis/install-std-race.sh
   - ./hack/build-go.sh
   - go get ./contrib/podex
 
 script:
   - KUBE_TIMEOUT='-timeout 60s' ./hack/test-go.sh
-  - PATH=$HOME/gopath/bin:./third_party/etcd/bin:$PATH ./hack/test-cmd.sh
-  - PATH=$HOME/gopath/bin:./third_party/etcd/bin:$PATH ./hack/test-integration.sh
+  - PATH=$HOME/gopath/bin:./third_party/etcd:$PATH ./hack/test-cmd.sh
+  - PATH=$HOME/gopath/bin:./third_party/etcd:$PATH ./hack/test-integration.sh
   - ./hack/benchmark-go.sh
 
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