Revert "Vim: Plug-in: NeoComplete"

This reverts commit 1de8b504714562c744335c34bdad1a7c97c5c139.
Revert "Vim: Plug-in: jedi-vim"

This reverts commit 5925e936294974b3371d1888b3098bb1499a79d6.
Vim: Plug-in: YouCompleteMe
Update submodules