feat(progressbar): add `bar` directive & refactor `progress`

 * Add `max` attribute for `progress`
 * Remove `onFull` & `onEmpty` handlers.
 * Remove automatic types and stacked types.
 * `progress` & `bar` transclude content to support text & extra elements.

BREAKING CHANGE: The onFull/onEmpty handlers & auto/stacked types have been removed.

  To migrate your code change your markup like below.

  Before:

  <progress percent="var"></progress>

  After:

  <progress><bar value="var"></bar></progress>

  and for stacked instead of passing array/objects you can do:

  <progress><bar ng-repeat="obj in objs" value="obj.var" type="obj.type"></bar></progress>