fixing firewall config to follow api documentation

Changed 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 traffice. These fields are included in documentation, but there is
no other field provided to accept ips.
Added missing health check uri and pool description
Merge pull request #2345 from alphagov/fixing_bugs_in_firewall_configuration

Fixing bugs in edgegate service configuration