Merge pull request #9 from GreatFruitOmsk/master

Under certain conditions exc_traceback can be empty or even None.
Fix tests, version/docs bump
Support enhanced user info in Py3
Enhanced user info in py2
Docs/version bump to 2.1.0
Update README.rst
Update README.rst
Make titles in README into headers

So they are linkable from Raygun
Added Raygun "undefined" workaround