Remove subdirectories to make space for submodules

So far removed:
 * tpope's plugins
   - abolish
   - afterimage
   - characterize
   - commentary
   - endwise
   - eunuch
   - obsession
   - repeat
   - rsi
   - speeddating
   - surround
   - unimpaired
 * msanders' snipMate plugin
Remove the rest of the subdirectories to make space for submodules

Directories removed:
    * NrrwRgn
    * bufexplorer
    * powerline
    * sparkup (there is a pathongen-ready version on GitHub)
    * solarized
    * todolist (consider replacing with cuteTodoList)
    * vim-latex
    * vimwiki
    * winmanager (depends on bufexplorer)
    * xml-vim (consider replacing with ragtag by tpope)
re-add previous bundles as git sub-modules