* Use docker to locally run tests on multiple perl versions
* perlbrew used to install multiple perls
* perl environments bootstrapped when image built
* Based on travis configuration
* Adds docker folder to MANIFEST.SKIP
* Running image runs all tests.
* If exit with no error, then all tests pass.
* ./build-docker.sh builds stow testing image.
* ./test-docker.sh runs stow testing image.
* Assumes built with options in build-docker.sh
* *-docker.sh scripts added to MANIFEST.SKIP
