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