Changing topic to webrequest_mobile, now subscribing to config file

Camus creates directory imports based on topic name.
hive-partitioner tries to match directory names with
hive table names.  Hive will not allow creation
of tables with hyphens '-' in the name.  Changing
mobile varnishkafka topic to 'webrequest_mobile' fixes this.

Also, varnishkafka now subscribes to its config file(s).
This will ease changes, as puppet will reload varnishkafka.

Change-Id: Ie71ec496ff9ba09830ceca9ff1137526ac63c26f