Allow using a custom requests Session instance.
Support Python 3.
Bumping version of python-dateutil to 2.2

python-dateutil 2.2 now works on Python2 and and 3.
All tests are passing

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>
Merge branch 'custom-session' of https://github.com/miracle2k/reppy
Merge branch 'python3' of https://github.com/miracle2k/reppy

Conflicts:
	reppy/__init__.py
Merge branch 'dateutil_upgrade_to_22' of https://github.com/pombredanne/reppy
Add travis, tox, requirements

Conflicts:
	setup.py