Checkboxes

tldr: Added checkbox group input

Created a new template called ‘checkbox_group’ which creates a checkbox
field using the options.
A second template called ‘checkbox_group_scroll’ is called if
attributes[‘scroll’] is true. This adds a .scroll class which allows
for CSS.
Moved logic from Form to Form Helper

There were some odd changes going on when I tried to manage checkboxes.
I duplicated the drop down method.
Merge pull request #2 from jonathanstegall/develop

new checkbox thing