Support more slim select options

Problem/Motivation

There are far more options to support, see https://github.com/brianvoe/slim-select/tree/61dd471ce0240c7368198082386...

Proposed resolution

Lets change slim-select.js so that it passes all attributes without nominating, this way even if the api changes it will still work

Remaining tasks

change slim-select.js, provide testing.
For the testing I think it is redundant to test each configuration functionally, I think that beyond the basics we should just check that the form options where passed to the SlimSelect object because that it this nodules job.