[examples] Added error handling to the trib app for models and templates for errors and when no results are returned.

The models of the mojits Blog, Calendar, Gallery, Github, and Youtube would occasionally not return results because of an issue with YQL or the original data source. Because the models didn't handle this case, the app would fail. Two shared templates were added that mojits could use to render HTML when there was an error or no results.
In addition, an error in the Calendar model that incorrectly parsed a string to extract a date was corrected.