change port option from Opt to IntOpt
change port option from Opt to IntOpt

this change alleviates the warning produced by oslo-config-generator
from the port option by incorporating the integer minimum and maximum
into the configuration option.

Change-Id: Icd14219f86a00666af2f8ef6ac00d8fbf31d1676
Closes-Bug: #1517211

egafford/sahara,tellesnobrega/sahara,openstack/sahara,egafford/sahara,openstack/sahara,tellesnobrega/sahara