Remove Plek from bundle

OK, so this is weird, but I think I know what's going on. Plek is getting pulled in before Dotenv-rails loads, so the ENV variables don't get loaded in properly, and Plek thinks we're running https. So I've removed Plek from the bundle (it gets loaded in as a dependency anyway), and things seem to work. Weird that it doesn't happen in any of the backend apps though.