Lots of fixes. Looking towards the future.

• Hide customizer fields by default while still under development.
• Fix Issue 123 - Language translations to actually function properly embedded as well as in the plugin.
• Fix Issue 151 - Media field uses thumbnail not full image for preview. Also now storing the thumbnail URL. Uses the smallest available size as the thumb regardless of the name.
• Fix Issue 147 - Option to pass params to select2. Contributed by @andreilupu. Thanks!
• Added trim function to ace editor value to prevent whitespace before and after value keep being added
• htmlspecialchars() value in pre editor for ace. to prevent html tags being hidden in editor and rendered in dom
• Feature: Added optional 'add_text' argument for multi_text field so users can define button text.
• Added consistent remove button on multi text, and used sanitize function for section id
• Feature: Added roles as data for field data
• Feature: Adding data layout options for multi checkbox and radio, we now have quarter, third, half, and full column layouts for these fields.
• Feature: Eliminate REDUX_DIR and REDUX_URL constants and instead created static ReduxFramework::$_url and ReduxFramework::$_dir for cleaner code.
  Feature: Code at bottom of sample-config.php to hide plugin activation text about a demo plugin as well as code to demo how to hide the plugin demo_mode link.
• Started work on class definitions of each field and class. Preparing for the panel builder we are planning to make.