Don't report coverage to coveralls.io on Appveyor for PRs
Don't report coverage to coveralls.io on Appveyor for PRs

For coverage reporting on Appveyor it's necessary to set
COVERALLS_REPO_TOKEN env variable. For security reasons it's
not available when building pull requests, so don't call 'coveralls'
in that case. To compensate, always run 'coverage report'.

mpeterv/hererocks,mpeterv/hererocks