Allow the uri passed to various entrypoints to itself
contain most of the configuration for that entrypoint
by using the RFC 3986 uri format to allow for additional
parameters to be used in configuring and selecting those
entrypoints.
Also bring over network_utils from oslo since it provides
a more compliant url splitting support.
Part of blueprint persistence-uris
Change-Id: I8e5d8584d2cac4f9b338fa155f220cdfd52bb7d9