Improving help text for RPC opt
Improving help text for RPC opt

Adding improved help text for allowed_rpc_exception_modules opt.

Change-Id: I4bf2257cef7d99110e67aefa58dad9055e4dfccb
Partial-Bug: #1570946

openstack/glance,rajalokan/glance,openstack/glance,openstack/glance,stevelle/glance,rajalokan/glance,stevelle/glance