Improve element parsing

[rowanseymour]

• Adds support for classes being before ids (fixes Element id is ignored when given after classes jessemiller/HamlPy#126)
• Adds support for tags with hyphens (fixes Should support tag names with hyphens #6)
• Element class now stores unrendered state and render_attributes does rendering of HTML attributes when required. This makes it easier to test.

[coveralls]

Coverage increased (+0.02%) to 77.766% when pulling 4238b21 on classes_before_ids_2 into cf8c454 on master.

[coveralls]

Coverage increased (+0.02%) to 77.766% when pulling 4238b21 on classes_before_ids_2 into cf8c454 on master.

[coveralls]

Coverage increased (+0.02%) to 77.766% when pulling b7ddfa1 on classes_before_ids_2 into cf8c454 on master.

[coveralls]

Coverage increased (+0.02%) to 77.766% when pulling 2bcf074 on classes_before_ids_2 into cf8c454 on master.

[rowanseymour]

@Psycojoker please review when you get a chance

[coveralls]

Coverage increased (+0.02%) to 80.485% when pulling 9880acc on classes_before_ids_2 into 3aafc5c on master.

[rowanseymour]

@Psycojoker sorry to pester but really want to get this merged this week if possible

[Psycojoker]

@rowanseymour gonna try to look at this this evening, sorry I'm really busy right now :/

[Psycojoker]

Sorry, took me a bit of time to fully review your changes. They do improve code readability, thanks for that :)

[Psycojoker]

Tell me if you feel confident enough for a release.

[rowanseymour]

Yes please make one

[Psycojoker]

https://pypi.python.org/pypi/django-hamlpy/0.86