Sort workers index page by name

This lets you easily scan the list to find a particular worker, especially when you have a large number of them.

I would love to include a test for this, but I'm not sure the best way to go about that. Since you're only doing plain `assert`s in the [test_web.rb](https://github.com/tobiassvn/sidetiq/blob/master/test/test_web.rb#L32) file.