more python3 updates

[bmcfee]

In this PR:

• 2to3
• Integer division where appropriate, from what I could tell
• key-based sorting for py3 compatibility
• relative imports for proper package encapsulation

I haven't tested thoroughly, but it's working as expected in my python 3.5 environment.

[firetix]

Can you look into adding this pull request it looks like it's working correctly for me