Upgrade to SDK 21
Improvements to the library view:
- Add imports to Library service object.
- Show imports in the library view.
- Only show label and corresponding list if the list is not empty.
Merge branch 'master' of github.com:johnmccutchan/observatory
Fix white space.
Address some review comments regarding dead code / refactoring.
Merge branch 'master' of github.com:johnmccutchan/observatory into evaluator

Conflicts:
	app/src/main/java/org/dartlang/observatory/LibraryView.java
More compact library view:
- Toggle visibility of list when clicked.
- By default the list is hidden in a new view.
Must not extract sub serviceobject before upgrading.
Merge branch 'master' of github.com:johnmccutchan/observatory into evaluator