In bug 749312, we were given permission to create a source readme
instead of a source tarball. This will save us cycles, disk, and
human configuration time.
We still need to address the missing balrog_props.json for
beetmover-source for that task to turn green.
MozReview-Commit-ID: wnyPoNXCsH
Other related changes:
* Only target.{zip,tar.gz,tar.bz} get the widevine signature (not the various installers).
* Linux{32,64}-nightly are now repackaged. Their mar files are not signed during signed step anymore. It now happens after the repackage.
* As a consequence, funsize routes for linux are now set to repackage-signing (instead of signing)
* Signed upstream artifacts are now defined in a dedicated module (to avoid duplication)
* Platforms defined in beetmover_repackage now allow regex (to reduce duplication too)
* Mozharness configs: Delete unused (and misleading) `src_mozconfig` for windows. This value is actually not used when `run_configure` (in the same dict) is set to False.
MozReview-Commit-ID: COKqevW9Mzn
