Support paging when fetching organization members

Organization members are a paged list in the V3 GitHub API. Previously the code would fetch only the first page of ~30 members and return that. This change switches the return to a PagedIterable<GHUser> so clients can fetch the entire organization's member list.
add a filter param to the get members method
Created new method to automate the merge
BugFix when listing repositories of a GitHub Organisation

Repositories of a GitHub Organisation are under 
/orgs/:org/repos as documented at:
http://developer.github.com/v3/repos/#list-organization-repositories

We need then to override the GHPerson implementation
which would have just returned the user's repositories.
Un-finalize GHContent.

GHContent was declared as a final class, which makes it impossible to mock with libraries like Mockito.
Fix GHIssue.setLabels() - *don't* set 'assignee' instead!
Support the check-user-team-membership API call

http://developer.github.com/v3/orgs/teams/#get-team-member
Add org public-members call, to complement the full members list

http://developer.github.com/v3/orgs/members/#public-members-list
Fix org.getMembers() to 'wrap' returned users for post-populating

This fixes an issue introduced with PR #66 in commit fee02a3d16 - the
`getMembers()` method switched to using paging, but lost the code that
populated the users with a full set of values.

This commit just applies 'wrapping' to all users returned, so that methods
like `user.getCreatedAt()` can be called on returned users without throwing
a NullPointerException - the reference to 'root' allows the user objects to
populate themselves.
need to populate enum
Added apis to list commits by author and list the repos of an organization (including the private ones)
change in comment
Added pagesize parameter to 'Get commits by author and branch' api
In order to handle http based github enterprise vm url, changing https to http
Keep the original signature intact for backward compatibility
Merge branch 'pull-76'
indentation fix
The parent commit appears to be totally untested.

The placement of the method makes no sense, and the API route is wrong.
The parameter is missing, and the expected response type is wrong.
Merge branch 'pull-69'
Fixed a bug in the databinding of the 'private' field.

Luca pointed out this bug in
https://github.com/lucamilanesio/github-api/commit/ae7a616e928e0646ea50e77b1792f835f93817f2