Python 3 compatibility update

Hello there folks, this pull request relates to issue https://github.com/cobrateam/splinter/issues/165

The pull request is still a work in progress but very close to completion.  I'll keep the status of everything below.

## Python 2.7 ##

- **Django**: OK
- **Zope**: OK
- **Chrome**: OK
- **PhantomJS**: OK
- **Firefox**: 1 error (which was present before my work)
- **Remote**: no ability to test this on my system, will wait for Travis results

## Python 3.3 ##

- **Django**: OK
- **Zope**: N/A dependent library not currently Python 3 compatible
- **Chrome**: OK
- **PhantomJS**: tests seem to lock up, investigating
- **Firefox**: 1 error, 1 failure (which were present before my work)
- **Remote**: no ability to test this on my system, will wait for Travis results

All questions are welcome :smile: 
Fotis