Added buttons helpers, usage:
btn 'A text', a_path_helper, class: 'my-class', ...
btn_primary 'A text', a_path_helper, class: 'my-class', ...
btn_danger 'A text', a_path_helper, class: 'my-class', ...
... is intended for additional options
fixed when options[:class] is nil
Merge pull request #1 from juanpastas/master

Buttons helpers