Explicitly exclude folders that cpack will incorrectly add to the RPM
file, see http://public.kitware.com/Bug/view.php?id=13609.
Clarify required use of ProtobufDecoder for inter-Heka communication.
Ugly hack, creating a custom `pkg` target that does exactly what
`package` does except it renames any debs after the packages are
built.
Make the custom target specific to deb packages.
Use cpack command flags instead of a shell script to change the deb
package file name, remove the shell script, don't generate a deb
package when running 'make package', and document the change.
Set and use CPACK_DEBIAN_PACKAGE_ARCHITECTURE in our deb file
(name instead of GO_ARCH).
Merge pull request #555 from mozilla-services/cpack-deb-rename-hack

Cpack deb rename hack
Version bump / prep for 0.4.2 release.
Merge tag 'v0.4.2'