Vendor: add rainbow-delimiters.el-506fef6

Note: 506fef6 is an abbreviated commit id in the git history of Rainbow
Delimiters.
Add "~/.emacs.d/vendor/" directory to load-path
Vendor: add js2-mode-20140114
Vendor: add git-modes-g1f0ae8f
Vendor: add magit-g4f46c97
Keep files from git-modes in the same directory
Add git-modes and magit directories to load-path