Enable all select2 api options

[davidstevens37]

Hey @iStefo, thanks for making this addon. you did a great job on it.

I understand you have limited time to work on this project, so i hope this is helpful. I added a comprehensive list of available select2 api options to pass when initializing select-2 v3.5.2 which will loop over and see if a user has defined the option, and if so it will include it in the initialization options.

I didn't bother cross-referencing what options can be used with which other options because i think that should be an issue handled by select-2, no?