Elevators v2

I was trying to set up a modded 1.7.10 server using Cauldron recently, and I discovered that my Elevators plugin doesn't work on 1.7.10 because of several differences in the API! So, I've made a special 1.7.10/1.7.x version, which I've tested and is fully working on 1.7.10.

The only difference you'll actually notice is that the signs are less colorful.

This is because the messages were too long to fit on signs in 1.7.10. (I think the max was increased in 1.8.)

Other than that, it's just basic API replacements, like removing the references to separate sounds for gate doors, replacing MaterialData stuff with raw data bytes, etc.