We can't build a static binary because that would require bundling the
closed source NVML library in cAdvisor.
Instead, gonvml uses dlopen to dynamically load NVML.
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
