vimrc: add new plugin manager, fix feature test

* Introduce Vundle and manage the ctrlp plugin with it.
* Fix bogus `has` usage, which does not check for executable availability.

Signed-off-by: Wayne Warren <waynr@sdf.org>
vimrc: Add more color keymappings.

Signed-off-by: Wayne Warren <waynr@sdf.org>
vimrc: Add Color-Sampler-Pack

Signed-off-by: Wayne Warren <waynr@sdf.org>