Add integration tests for existing allow/deny/net_out functionality

 - Add 'netdog' executable to test udp
 - Remove subnet_sharing_test as it's now subsumed by these tests

[#81502222]
Use checked-in, statically linked netdog

Thanks to Go 1.4, it is no longer possible to statically build
netdog. Until this is fixed, we check in a version built with 1.3

[#81502222]

Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com>
Merge branch 'networking-integration-tests-#81502222'

[#81502222]