Py3 support

Adds python 3 support (tested 3.2 and 3.3, see [travis](https://travis-ci.org/hayd/faker/builds/7377128)).

I removed all of the `u''`s since these are a syntax errors in python 3 <= 3.2 (they're fine in 3.3), this shouldn't be a problem since everything is ascii, but worth mentioning and perhaps changing if not ok.

*I put this on the top of the travis pr #4, so as to actually test it.*