Accepts any directory starting with VimTAP

I've just updated runVimTests and noticed that now it tries to detect the the VimTAP and runVimTests itself automatically, which is very nice.

While this works fine for `bundle/VimTAP`, it fails if the directory name is different, as `bundle/VimTAP-0.3/`. I prefer to keep the prefix to remind me that it is not the latest version of the plugin, as it is not in github.