Refactor common code in binary/recipe builds

[Michael Nelson]

As part of the buildfrombranch sprint, we've created a SourcePackageRecipeBuild which shares lots of code from the soyuz binary Build. Commonalities need to be refactored into BaseBuild where possible.

[Michael Nelson (michael.nelson)]

After looking through it, we can actually just move the whole thing onto BulidBase at the moment (and update the subclass later to deal with the manifest.)