fix(config): Fall back to the current SDK version for target packages.

This avoids loosing access to binary packages between tagging a new
version and finishing the build. The SDK's make.conf already does this.
Merge pull request #243 from marineam/release-reorg

fix(config): Fall back to the current SDK version for target packages.
feat(sys-kernel/coreos-kernel): bumpt to 3.10.17