This contains a few different builder manager fixes:
* Update the zip file structure to avoid an extra subdirectory
* Annotate packages with what functions are using them
* Only trigger builds when there is no deployment archive
* Python environment loadpath bugfixes
* Other bugfixes
This change orchestrates function builds.
Environments (in v2) define a builder image, just like they do a runtime image. The builder image contains a build script that's invoked with source and deployment paths (as env vars).
The buildermgr watches for environments with build images defined, and creates build deployments and services.
Functions can define source and deployment. Buildermgr watches for functions with source code (and build status == pending) and invokes the environment's builder when appropriate. It captures logs from the build and sets the build status (success/failure) and build lots into the PackageStatus.
