Make --repo-path an optional argument for db_recreate
Make --repo-path an optional argument for db_recreate

db_recreate uses repo-path to call db_sync, but for db_sync this
argument is optional so it should be optional for db_recreate as
well.

Closes-Bug: #1279734

Change-Id: I68b0eb3c705525a047eb6bffe8d5e1b4b083cd91

redhat-openstack/trove,mmasaki/trove,zhujzhuo/openstack-trove,zhujzhuo/openstack-trove,mmasaki/trove,fabian4/trove,hplustree/trove,zhujzhuo/openstack-trove,redhat-openstack/trove,fabian4/trove,mmasaki/trove,zhangg/trove,openstack/trove,fabian4/trove,cp16net/trove,cp16net/trove,redhat-openstack/trove,cp16net/trove,openstack/trove,zhangg/trove,hplustree/trove