Merge pull request #5 from infidel/master

Allow package name var (pkg) to be overridden by PACKAGE env var
Update README.md
Add debug messages
Remove the package after the tests
Add basic support for optional dependencies
first the depopts before, then the test run
More tweaks to better control the different steps
More tweaks
Improve README
More README tweaks
Fixes
Run tests by default
Merge pull request #7 from samoht/master

Add hooks for testing optional dependencies