Improved markup of index page, dropped useless libraries
Network errors when datasources are fetched are now correctly handled

The application displays an error message where the data should have
appeared if some network error occurs or if the application does not
receive any piece of data within 10 seconds.

Various other improvements:

- the events datasource was loaded 4 times in a row, now loaded only
once.
- various fixes in the Controller and Router not to trigger events
twice.
Added version of index page for development purpose

The "index.html" page uses the compiled version of the application.
The "index.dev.html" page references the source code directly and
is thus typically useful to develop the app.
Application built. Version bumped to v0.2.0
Merge pull request #1 from joshfire/feature/error

Handle errors while fetching Youtube data