Adds a big Xdebug button next to the Composer button

Puts xdebug front-and-center, although it's not installed by default
Adds js for the Xdebug button
Sets $installXdebug = false by default
Fixes improperly renamed tests, refactors new test
fixed merge conflicts
Merge branch 'jeremykendall-feature/xdebug-in-yo-face'