Vid 2079 prep gallery JS for outside usage

Setting up a better entry point for VE to consume media galleries. Now, in order to instantiate galleries, simply recreate the logic in controllers/index.js in whatever environment it is needed. 

@inez 
The comment notes that the options variable is optional. If the options are set, they are booleans, otherwise, being optional, they are undefined. As for a reason not to include ```|| false```, it's unnecessary, so it's just extra code.