Phoenix 1.3 support

[Qqwy]

I'd love to use this in a Phoenix 1.3 project.

Right now I am running Phoenix 1.3.0rc, and phoenix_haml works fine (but of course, as it states that it will only work with 1.1 and 1.2, it complained until I added override: true to the phoenix line in the mix.exs.

I expect that the only thing that requires changing to support 1.3 properly is to change the generators.