add checking intents function for SDN-IP

1. check both MultiPointToSinglePointIntent and PointToPointIntent
2. does not including check the ICMP path PointToPointIntent
3. check MultiPointToSinglePointIntent and PointToPointIntent seperately
4. we generate the all the expected intents base on the sdnip.json
5. after geting all the intents from ONOS CLI, then extract
   MultiPointToSinglePointIntent and PointToPointIntent seperately and
   change all intents into the same formats of intents we generated.
   The two types of intents use different formats.
You should call main.case("description") at the beginning of each test case