Use inheritance for overriding of builder args

This establishes a pattern for adding any number of combinations for the
new build script to use. Each individual test class may be called
separately to only do builds of a select type. An example testr command
looks like:

testr run '^(test_build.BuildTestCentosBinary)' or even more simply
testr run test_build.BuildTestCentosBinary

Change-Id: I828a8c9c36a771bd5ad23e0dee6dffe3e94067e1
Paritally-Implements: blueprint gate-source-builds