Add an option to indent with tabs instead of spaces

I can't see an easy way to get this into the shortcuts and have no run
the unit tests. Please excuse my python inabilities.
Remove the button synonym

Remove button as a synonym for an input with type button. Button is a
perfectly good element in it's own right.
Turn the spaces in shortcuts into tabs

This will probably break the unit test and is not adjustable by
options. Not recommended.
Merge pull request #59 from dmnc/master

Allow tab indentation rather than using spaces