Add support for Haml attribute methods

[jeremyhaile]

Similar to HAML attribute method

I'm currently running into a case where I want to do something like this but it isn't supported by haml-coffee:

%button{data: @model.dataAttributes()}

or

%button{@attributes()}

@netzpirat mentioned this in #57 but I didn't see an issue tracking it.

[buzzijavier]

Bump +1

[buzzijavier]

Aww. Crap. I just read that the dude passed away. This project is going to die if someone doesn't pick it up.

[jeremyhaile]

@buzzijavier are you saying that @netzpirat passed away? Where did you read that?

[vendethiel]

See #97

[vendethiel]

Also, I'm not maintaining since because I havn't used it since my first PR, but if any of you guys want to work on this, I'll always be here to merge etc.