Python 3 support, and more

Orlo is now testing and working against Python 3.5. At present I still recommend using 2.7, as this is the primary target platform, but I expect this to shift as Ubuntu Xenial is more widely adopted.

This tag is published as the same version on pip.

In addition to a plethora of bug fixes, there is now support for authentication with tokens, but it is not well tested or documented. See the git log for details, I try to keep it relatively tidy.