travis: split param check for each vehicle

the param_parse Python script has bugs when trying to parse all vehicles at once, so make each one at a time
use the new option so that only validation is performed

.travis.yml

@@ -44,7 +44,11 @@ before_install:
   - if [ "$TRAVIS_EVENT_TYPE" = "cron" ]; then export CI_CRON_JOB=1 ; fi
 
 script:
-  - python Tools/autotest/param_metadata/param_parse.py
+  - python Tools/autotest/param_metadata/param_parse.py --no-emit --vehicle APMrover2
+  - python Tools/autotest/param_metadata/param_parse.py --no-emit --vehicle AntennaTracker
+  - python Tools/autotest/param_metadata/param_parse.py --no-emit --vehicle ArduCopter
+  - python Tools/autotest/param_metadata/param_parse.py --no-emit --vehicle ArduPlane
+  - python Tools/autotest/param_metadata/param_parse.py --no-emit --vehicle ArduSub
   - Tools/scripts/build_ci.sh
 
 before_cache: