Implementation of replication servers

Support separate replication ip address:
- Added new function in utils. This function provides ability
  to select separate IP address for replication service.
- Db_replicator and object replicators were changed.
  Replication process uses new function now.

Replication network parameters:
- Replication network fields (replication_ip, replication_port)
  support was added to device dictionary in swift-ring-builder script.
- Changes were made to support new fields in search, show and set_info
  functions.

Implementation of replication servers:
- Separate replication servers use the same code as normal replication
  servers, but with replication_server parameter = True.  When using a
  separate replication network, the non-replication servers set
  replication_server = False.  When there is no separate replication
  network (the default case), replication_server is not included in the config.

DocImpact
Change-Id: Ie9af5bdcdf9241c355e36053ca4adfe49dc35bd0
Implements: blueprint dedicated-replication-network
Merge "Implementation of replication servers"