[Builder] github integration

[MohanR <mohan43u gmail com>]

Hi,

I'm that guy who started a bug report to add goa provider for github
https://bugzilla.gnome.org/show_bug.cgi?id=741684 and suggested by goa
developers to make gnome-builder work with github, so that they can add
the goa provider patch.

I can write a GObject wrapper for github api (I have written it already
in javascript for a simple gnome shell extension
https://extensions.gnome.org/extension/917/gistnotes/), but I'm not
clear about the purpose gnome-builder needs to interact with github. I
can think of few,

1. github code search (https://developer.github.com/v3/search/) : search
the code in github.
2. issues (https://developer.github.com/v3/issues/) : see/fix the issues from builder
3. pull requests (https://developer.github.com/v3/pulls/) : handle pull requests from builder
4. notifications (https://developer.github.com/v3/activity/notifications/) : get instant notification from 
github
5. gists (https://developer.github.com/v3/gists/) : store small test code (or) use github as a personal 
pastebin

I also like to know whether is this the right time to do all these changes
or we have other idea (like writing a plugin instead of implementing in
the base code).

Thanks,
Mohan R