BROOKLYN-55 install script for brooklyn

Should we really be using `AnyoneSecurityProvider`? Or should we generate a new password? Or upload a pre-defined `admin:password` combo that uses the hashed password approach (and obviously write out at the end of this script what that credential is)?

FYI see @sjcorbett 's recent change for https://github.com/apache/incubator-brooklyn/pull/154. But we'd need to write out the user:password at the end of this script (rather than just in the remote host's log), so not applicable here.