README update: terminology and doc links
Merge pull request #163 from mesosphere/terminology

README update: terminology and doc links
Use v2 API in haproxy_cfg
- Added version (timestamp) to AppDefinition
- Updated protobuf to include a required version (string) in a ServiceDefinition
- Added Versioned and Timestamped traits
- Added a Timestamp ADT backed by a Joda DateTime, custom serialization
Added History type
Add githalytics
- Added a proto definition for AppRepository (list of apps versions), re-ran protoc.
- All versions of apps are now persisted, added endpoints to list and show old app versions, app update (PUT) supports rollback based on a version in the JSON body.
- v1/EndpointsResource no longer depends on MarathonStore.
Updated REST docs to reflect new API endpoints.
Formatting and link fixes in REST docs.
REST doc link fixes.
Factored out unnecessary abstraction in the state subpackage.
Fixed protobuf definition for AppRepository.
Updated docblock comments in the state subpackage to reflect refactoring.
Made UTC conversion internal to Timestamp initialiser.  Added tests for new data types in the state sub-package.
Merge pull request #166 from mesosphere/wip-versioned-apps

Versioned apps
Fix for #167. Return '201 - Created' from POST /v2/apps rather than '204 - No Content.'
Merge pull request #169 from johanatan/master

Fix for #167. Return '201 - Created' from POST /v2/apps rather than '204...