Actually, this is fixing examples for browsers without <template> and Object.observe.

Many were suffering from: https://github.com/Polymer/mdv/issues/64 and also lack of calls to Platform.performMicrotaskCheckpoint().

Also, the twitter rest API 1.0 is now gone and the 1.1 API requires auth, so I removed the example for now.

R=arv
BUG=

Review URL: https://codereview.appspot.com/10383044