The integration test script was changed so that it aborts the testing
when the cAdvisor binary exits with a non-zero error code.
Also in this PR:
- clean up makefile to print more informative output
- change make release to build the release binary
- Eliminate version/VERSION in favor of parsing git versions
- Enforce that releases are built against tagged versions
- Delete the broken release script, change `make release` to build the release
