Bug 1054437: Add contribute numbers to settings and global context.

This is just for the hard-coded numbers until we get them automated.
Bug 1080634 - Update the Install link to point to a more relevant help page + Provide different URLs for Desktop & Mobile
Bug 1049856: Add convenience methods to events app.

For home and contribute pages.
Merge pull request #2359 from pmclanahan/add-events-convenience-methods

Bug 1049856: Add convenience methods to events app.
Merge pull request #2357 from pmclanahan/hard-code-contrib-numbers-1054437

Bug 1054437: Add contribute numbers to settings and global context.
Merge pull request #2350 from sylvestre/master

Bug 1080634 - Update the Install link to point to a more relevant help p...