Add 'slave_of' option for enabling replication

Add a new create option (--slave_of) that can be used to enable
replication and configure the newly created instance as a slave of the
specified existing instance.

DocImpact Introduces new option when creating an instance.

partially Implements: blueprint replication-v1
Change-Id: Idf22d3d9e676138969cbdf3afd4903b8e475c313
Merge "Add 'slave_of' option for enabling replication"