Remove jQuery document.ready

Everything is fine, everything still works.
Refactor Github plugin into it's own plugin
Refactor Dropbox plugin into it's own plugin
Refactor GoogleDrive plugin into it's own plugin

Also cleaned up GoogleDrive file with spacing of 4
Moved Notifier into it's own file
New Plugins module to handle plugin management

This is the initial code to handle how Plugins will communicate to
Dillinger.
Favicon fix on invalid page loads

There are times where if express returns a page error, there is an
error in the console complaining about not being able to find the
favicon file. This fixes that problem.