Rename coverage.sh to .coverage.sh (#270)

This is "infrastructure/meta" code, don't need to see it.

.travis.yml

@@ -47,7 +47,7 @@ script:
   # Run kubernetes integration tests only if kubectl is available. i.e. If kubernetes was launched
   - ./contrib/kubernetes/testscripts/kubectl version && go test -v -tags k8s -race -bench=. -run 'TestK8sIntegration' ./test
   # go cannot use test profile flag with multiple packages so we have to iterate, the following might be consolidated with the above steps.
-  - ./coverage.sh
+  - ./.coverage.sh
 
 after_success:
   - bash <(curl -s https://codecov.io/bash)