- "transcient bundle" - a bundle installed with :BundleInstall or interactively
without being declared in .vimrc
- treat them the as if they were configured
- so everything works the same
- ie before this change helptags weren't generated automatically
with `BundleInstall bundle` or with interactive mode
- it changes the way `:BundleClean` works, since it removes directories
that aren't bundles
- FIX: `:source .vimrc` to let `:BundleClean` remove transcient bundles
- closes#99
162b1bdd4f