Python 3 support

[vkurup]

Mostly minor fixes to provide Python 3 support. This is built on top of #453.

Will probably also need doc updates, but wanted to get this out there for review in the meantime.

[coveralls]

Coverage increased (+0.76%) when pulling 08749bc on feature/python-3-support into 7e9c49e on develop.

[dpoirier]

Github seems to be showing a whole lot more commits in this pull than I think were intended to be part of it?

[vkurup]

Yes, this is built on top of #453. Only the last commit is for Python3 support.

[mlavin]

This is awesome. The setup.py should probably also be updated with Python 3 related classifiers: https://github.com/rapidsms/rapidsms/blob/develop/setup.py#L49. Is 2.6 still supported?

[vkurup]

Thanks, Mark! Python 2.6 is still supported, but only with Django 1.6, since that's what's included in the Django compatibility page: https://docs.djangoproject.com/en/1.7/faq/install/#what-python-version-can-i-use-with-django

[coveralls]

Coverage increased (+0.76%) to 84.86% when pulling 7a273cc on feature/python-3-support into 7e9c49e on develop.

[lsgunth]

I've got a new server with Django 1.8 and python 3.2 running this code. It's so far working well (with the couple pull requests I've issued). Please release it as soon as you can.

Thanks,

Logan

[coveralls]

Coverage increased (+0.76%) to 84.86% when pulling 68dcdd7 on feature/python-3-support into 7e9c49e on develop.

[coveralls]

Coverage increased (+0.76%) to 84.86% when pulling da4a584 on feature/python-3-support into 7e9c49e on develop.

[vkurup]

Any other comments on this PR? If not, I'll plan to merge in about a week or so, since I know it's gotten a decent bit of review already, and seems to be working. Thanks!

[coveralls]

Coverage increased (+0.72%) to 84.82% when pulling 14ea9c0 on feature/python-3-support into 7e9c49e on develop.

[thedrow]

@vkurup If you don't mind please release a new version after merging this.
We're upgrading to Python 3 soon and we'd love to keep RapidSMS in our infrastructure.

[vkurup]

Sorry for the delay on this. I'll work on getting a release out.