Revert "Merge commit '0fc6408d8192c0a83f020404ba1eb41cbf9cd1ed' as 'vim/bundle/webapi-vim'"

This reverts commit 1871bd35ac930f82ef312cc3f479233212539d8a, reversing
changes made to 3721800c3107a335acadcf1a85a485aae02a29dd.
Switch webapi-vim from a subtree to a submodule