Adding since and until arguments for iter_commits to allow time range based iteration
[refs #112] Wrapping StringIO with an adaptor to deal with change to the method signature expected by requests
[refs #112] Using default value for chunk size to match StringIO behaviour
[refs #112] Can't use super with an old-style class
[refs #114] Fixing date creation for python 3 (leading 0 for numbers is not allowed)
Updating all timestamp parameters to accept either a datetime or an ISO-8601 date string
Using etag value in iter_repo_issues
Adding some unit tests for the timestamp_parameter util
Fixing isisntance check for strings depending on python 2 or 3 version
Fixing timestamp_parameter unittest for python 2.6 (there is no assertIsNone method)
Fixing timestamp_parameter unittest for python 2.6 (there is no assertIs method)
Parsing timestamp value before setting it as a parameter to prevent None being used as a parameterin requests
Merge remote-tracking branch 'github/pr/116' into develop
Fix doc-strings so Sphinx doesn't get confused.
Merge branch 'pr/114' into develop
Allow for per_page to be passed in certain methods

iter_all_users and iter_all_repos now accept per_page integer values and
GitHubIterator now handles paramter sanitization (removal of None) to reduce
repetition.
100% coverage and fixed tests
Fix the docs so code examples work properly.
Attempt again to fix RTFD.