drawer: fix "browse more" card:// redirect

Note, HOSTNAME is now HOST, with the fully qualified host (including port)
Yeah that logic probably shouldn't have been moved into this method. It is necessary overall though, because we're we're not on http://clay.io in Kik, we want to use http (since it's being opened in a picker). That should be specified in the getMarketplaceBase call though since there's now support for passing protocol.

Also, you should do that (pass http instead of card if it's from a subdomain) https://github.com/claydotio/clay-mobile/blob/master/src/coffee/components/drawer.coffee#L87