Validate executor pattern

Pattern is taken from AppDefinition.scala.
Render modal in React based off state

* `AppListComponent` polling start/stop is entirely handled in
  `Marathon`. No longer need to do that in the AppList.
Remove unneeded jshint comments

The content below is no longer JSX; it’s plain old JavaScript.
Improve executor pattern msgs to be human readable

Humans don’t like reading regexs (particularly the human named Michael).
Merge pull request #533 from mesosphere/validate-executor-pattern

Validate executor pattern
Correct capitalization of ZooKeeper in README
Merge pull request #537 from mesosphere/state-based-modal

Render modal in React based off state
Compile JavaScript currently in master
Merge branch 'master' into deployments-ui

Conflicts:
	src/main/resources/assets/js/components/Marathon.jsx
Changing url to include app def in task poll
Re-adding update on task fetch success