Properly fix the split dropdown

I've implemented a quick solution to having split dropdowns in GL-UI. We need a better fix that fits into our design guidelines a little better and removes the inline style from the component.

However, I'm not sure what that fix is and I needed split dropdowns for a main deliverable.

This issue is my reminder to clean my (mostly tidy) mess up.

The following discussion from !190 (merged) should be addressed:

• @winh started a discussion: (+1 comment)

  should we create an issue for the untemporary fix and link it here?