Support for Notebooks and Sublime Text 3

I thought you might be interested in Sublime Text 3 support, and support for saving a note to a particular notebook. This plugin does both. 

I haven't been able to test these changes against Sublime text 2, because I do not have a copy of it. But, the Sublime Text 3 support was mostly added by way of "if sys.version_info.major == 3" statements, so the Sublime Text 2 support should not be (very) broken.

The plugin will also now give a "quick list" at commit time, which will allow the user to choose a notebook in which to save the note.