removing additional whitespaces in <button> markup
Adding ButtonTypeExtension which:
* fixes double 'type' in markup bug
* allows usage of BS-Button styled <a>-Tag
* (+1 squashed commits)

Squashed commits:

[6f1d0e4] renaming button extensions new options for better clarity
Merge pull request #286 from derpue/form_actions_patch

Form actions patch