Added compatiblity with Stag Custom Sidebars

Displays an options in Shortcode builder dropdown to choose widget area
if the plugin Stag Custom Sidebars is active.
Fix: Properly resize the thickbox window height
Refractor Code
Added tags and a few things
Added options to add font icon in button shortcode

Along with an option to display the icon before or after the text.
Added icon order class to button shortcode

To give the icon left/right margin depending on the shortcode option
Shortcode style tweaks based on user feedbacks
Added Sass
Added doc
Fix Image/Video Media frame title