[vcloud_director] fixing firewall config to follow api documentation

Change include following fixes:
1. policy, description and port fields are not mandatory.
2. Request layer should be dump and should not do smart handling of
data. Accepting data in same format as documented in api doc =>
https://pubs.vmware.com/vcd-51/index.jsp#doc/index.html
3. SourceIp and destinationIp fields are used to control source and destination
for traffic. These fields are included in documentation, but there is
no other field provided to accept ips.