[Bf-python] Include Contrib Addons for Testing Builds?

[Campbell Barton]

So far its great that we're able to more freely add developers but Id
like their work to be better tested.

Heres my proposal for including addons_contrib/ in blender for testing
builds only.

http://wiki.blender.org/index.php/User:Ideasman42/ProposalAddonsContrib



With this, a new developer can tell someone,
 "Hey, take a look at this addon I wrote, its called *some_addon*,
just download from graphicall and enable `Testing` in addons panel",

Otherwise they need to mess with svn, or downloading zips, blender may
be older then the addon supports - its just annoying.

-- 
- Campbell