Adding since and until arguments for iter_commits to allow time range based iteration
[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
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
Fix doc-strings so Sphinx doesn't get confused.
Merge branch 'pr/114' into develop