Add a bare bones VIM plugin script for YAPF.
Add a bare bones VIM plugin script for YAPF.

dmoliveira/yapf,nikolamilosevic86/yapf,wklken/yapf,lucius-feng/yapf,elviswf/yapf,sbc100/yapf,bygloam/yapf,sbc100/yapf,thurday/yapf,jamesblunt/yapf,google/yapf,google/yapf,hayd/yapf,ambv/yapf,abduld/yapf