Prepares for Python 3 support.

Squashed commit of the following:

commit c1e47a8cdeef52a22b08bc9cd1e15c6bb8852ae5
Author: Christopher Foo <chris.foo@gmail.com>
Date:   Fri Nov 15 22:19:04 2013 +0800

    Remove python 3 travis testing. Fix version_info check.

commit b666f294601eff7755a8b6be784b763c186f4a0d
Author: Christopher Foo <chris.foo@gmail.com>
Date:   Fri Nov 15 22:02:11 2013 +0800

    Fix travis config

commit ff7059d36962b8a0d5e83d21d23a1d01d5049f50
Author: Christopher Foo <chris.foo@gmail.com>
Date:   Fri Nov 15 21:58:54 2013 +0800

    Configs Travis to execute 2to3