Implement pagination on list of private+public repos of a user.

The paginated version of listRepositories() was 
missing at GHMyself: as side-effect of this bug
when requesting a paginated list of repositories
the ones privately owned by a user were not shown.

This was caused by the missing override of the 
listRepositories(final int pageSize) at GHMyself
that caused the GHPerson implementation to invoked.

The GHPerson version uses the /users/:org/repos?per_page=x
URL which *works fine* for organisations but unfortunately
*does not return* private repositories for users.

IMHO GitHub API are quite inconsistent form this 
point of view, but they are documented in this way
so that work (inconsistently) as designed.