update travis: dont manually install vet or cover

.travis.yml

@@ -29,8 +29,6 @@ go:
 
 install:
   - pip install --user cql PyYAML six
-  - go get golang.org/x/tools/cmd/vet
-  - go get golang.org/x/tools/cmd/cover
   - git clone https://github.com/pcmanus/ccm.git
   - pushd ccm
   - ./setup.py install --user