Created configuration helper

Finished changes from #500. I left switch statement in helper in this branch, but I also tried how it will look like, if switch statement would be in view partial - result: [branch](https://github.com/romanblanco/manageiq/compare/erb2haml3_opt2) | [diff](https://github.com/romanblanco/manageiq/commit/dd67abc6be96571d556a52b389f18e6314b3e1f2)
@Fryguy, here's the helper you're thinking about:
https://github.com/ManageIQ/manageiq/blob/master/vmdb/app/helpers/application_helper.rb#L2443

@martinpovolny wrote it originally, I implemented and tweaked it a bit.