Merge pull request #21 from jeluard/master

Support for Rate Limiting
add the three routes from the contents API
Merge pull request #22 from ngrunwald/contents

add the three routes from the contents API
added handling of useful headers information as meta on responses, and
support for conditional requests
added api-meta and updated tests
adds support for getting all repositories.

Hit /repositories end-point to query for all repositories as per api
docs http://developer.github.com/v3/repos/#list-all-repositories.
Merge pull request #24 from jakemcc/master

Adds support for querying for all repos
Inc version.
Merge pull request #23 from ngrunwald/conditional

Adds support for conditional requests and new way of checking rate limits
Added a simple helper function for gists.