Update dotfiles

After looking at other dotfiles, I realized mine could be done better.
Add Vundle as submodule.
Ingore vim bundles.
Update bootstrap script to work with submodules.
OS specific dotfiles
Load ~/.bash.d files.

I use a folder called ~/.bash.d to put anything I want loaded in my
environment, but don't want in my dotfiles. Load these files if the
directory exists.

Added -maxdepth option to DOTFILE *.bash loads, so unwanted things don't
get loaded by accident.
Cleanup.

Remove old dotfiles things we're not using anymore.
Source ~/.bash_profile after installing dotfiles

Loads dotfiles changes automatically.

Update PATH to include ~/bin