Configure plugins by name

To configure core plugin or service plugins, instead of using class names,
simpler names can also be used, ex:

service_plugins = router, firewall, lbaas

For compatibility with previous versions, the class name of a plugin can be
specified instead of its entrypoint name, ex:

service_plugins = router, neutron.services.firewall.fwaas_plugin.FirewallPlugin, lbaas

DocImpact

Implements: blueprint config-plugin-by-name
Change-Id: Ia4aaa1d305b160a4d6dab9e227c744727a4c78c2
Update RPC code from oslo

The common RPC code has been updated to include the following:
    8575d87af49ea276341908f83c8c51db13afca44
    8b2b0b743e84ceed7841cf470afed6a5da8e1d07
    23f602940c64ba408d77ceb8f5ba0f67ee4a18ef
    6d0a6c3083218cdac52758a8b6aac6b03402c658
    7cac1ac1bd9df36d4e5183afac3b643df10b1d4d
    8159efddabb09dd9b7c99963ff7c9de0a6c62b62

Updated to include the following in modules in openstack-common.conf:
py3kcompat, sslutils, and versionutils.

The update also includes imports from the RPC code

Change-Id: I84c5b8e2b17da0018dd69ecb354d123a609afe98
Merge "Configure plugins by name"
Merge "Update RPC code from oslo"