Change config file `source`ing

* Remove redundant `source`ing of `.vimrc.bundles.local` and `.vimrc.bundles.fork` from `.vimrc` (found in `.vimrc.bundles`)
* Move the `source` commands for `.vimrc.before.local` and `.vimrc.before.fork` into the `.vimrc.before` config file

Additionally cleaned up `.vimrc.bundles` slightly