Add Vundle configuration

Everyone will need to figure out how to remove the submodules they don't
need or just delete their repo and start fresh.

[Finishes #53046167]
Delete all git references to bundle submodules
Remove pathogen
Adjust bundle comments to prevent warnings

* Also update comment to refer to Vundle
Update README to reflect switchover to vundle
Don't ignore bundle/vundle as a submodule
Lock vundle submodule to master branch
Merge pull request #18 from pivotalcommon/switch-to-vundle

Switch to vundle