Resolve config file FIXME in vland protocol
The lava-vland protocol has a FIXME to allow the default vland_hostname of 'localhost' to be overridden in config.
Resolve this, including support for the port number as well.
Note: only to be started once vland has security to support access other than localhost.
Sub task of #5
Migrated from https://projects.linaro.org/browse/LAVA-550