non-spotify specific master resolution

* Remove spotify specific srv format and domain.
* Make the srv format configurable via a HELIOS_SRV_FORMAT environment
  variable.

dnsjava uses the dns search list in /etc/resolv.conf, so users in
environments with correctly configures dns search domains will not need
to enter fully qualified helios domain names during normal use.
Merge pull request #33 from spotify/dano/non-spotify-specific-master-resolution

non-spotify specific master resolution