Better goveralls Travis CI integration

Signed-off-by: Tim Waugh <twaugh@redhat.com>

.travis.yml

@@ -1,11 +1,9 @@
-sudo: false
 language: go
-install:
-  - go get golang.org/x/tools/cmd/cover
+sudo: false
+before_install:
   - go get github.com/mattn/goveralls
   - go get -t -v ./...
 script:
-  - go test -v -covermode=count -coverprofile=coverage.out
-  - $HOME/gopath/bin/goveralls -coverprofile=coverage.out -service=travis.ci
+  - $GOPATH/bin/goveralls -service=travis-ci
 notifications:
   email: false