BundleInstall sources the current vimrc in order to reload all Bundles
in order to consider new Bundles that might have been added by the user
directly on their vimrc file. This, however, should not be Vundle's
responsibility, changes in vimrc should not be applied unless it is
re-sourced explicitly by the user.

This makes Vundle use the known list of Bundles for installation.

- but don't like it

- TODO: refactor: extract common code

Installer buffer is marked as modified after each installation. Mark it
as nomodified so that no warnings are shown when the buffer is closed.

- otherwise confusing with updated

- to display message properly

- > active
- + updated
- . up to date
- ! error

- ! is error
- . is up-to-date
- * is updated

- rename statuses to be:
* error
* uptodate
* updated

- instead writing to file and opening it
- faster and has nicer status name

- TODO unify

- otherwise it defautls to vim-scripts repos
- closes #69
- TODO: pass options aswell

- add status to return values
- check status to see if bundle installed

- do not redraw on errors
- echo error during installation

- just show the message
- closes #46

- closes #45
- add /d swithc to cd command to perform drive change
- eclose joined commands with quotes

no new bundless installed => no new bundles installed.

- append slash to indicate directory, so expand ingnores wildignore
settings

- closes #21