Added Vundle functionality to manage plugins

- Installed vim-nerdtree-tabs plugin to browse file tree.
- Windows now open to the correct size with nerdtree-tabs installed.
- Made MacVim a little transparent, gvim is opaque.
Updated readme and install script.
Updated vertical split colors.
Updated dk1 color scheme

- NERDTree colors match terminal color scheme (blue for directories,
  green for executable files, white for other files).
Merge pull request #1 from dkong1796/vundles

Vundles