Fixed create_port with fixed_ips for public network

RM9593
RM9725 update

Modifies the traceback shown to the user when an
ethertype/remote_ip_prefix mismatch occurs.
Merge pull request #234 from sumanthns/fix_create_port

Fixed create_port with fixed_ips for public network
Merge pull request #239 from Cerberus98/master

RM9725 update