Create _vim/_vim and _vim/.vim on install

_vim/_vim and _vim/.vim were hard coded to a directory on your machine, so they need to be created on install to reflect the actual location on the user's drive. This shouldn't depend on my previous pull request, but it does change the same files, so you may want to look at that first.  I don't know how I should have done this, but these changes need to be cherry picked or manually merged.  Let me know if you want a plain old patch instead of this weird github interface.  I don't know how to not shove my username and dotfile preference changes with this without referencing a commit only on my branch.  If you have any advice or if this works, let me know.