github v3 api required as of may 1

[n8han]

Github is switching off their v2 api May 1. This is the version that all currently published versions of giter8 (and conscript) use so we are in for some breakage.

https://github.com/blog/1090-github-api-moving-on

I just made a first pass at converting to v3 and things seem to work. I would really appreciate it if someone could pull the changes and test specifically for binary files in templates, and also for private repos, and anything else you care about. I think we may need to revert to name/pass for private repos.

Nathan