what was I thinking...?!

This reverts commit 035cc6ecba.

- unify search and browse unders same interface

- ie, like this
Bundle 'gmarik/vundle'

- map modifies source collection
- arrays are passed by reference
- resulted in remapping g:bundles into list or directories

- was beaking case when bundle is already installed(downloaded) but not
configured
- should not affect other cases as adding require is pretty safe

- this was intended for case when user uncomments installed `Bundle` and
reloads .vimrc; which should make the bundle available
- TODO: later

- pass booleans instead '!'

- BundleClean now requires confirmation

- removes unused directories

- fixes https://github.com/gmarik/vundle/issues#issue/3
- TODO: not the most efficient approach