(RE-1497) Remove quantal from build_defaults

This commit removes quantal from all build defaults because it is end of
life. It removes the defaults from the build_defaults yaml.
Merge pull request #200 from clantant/RE-1497/master/srcs

(RE-1497) Remove quantal from build_defaults
(MCO-366) Remove Sid/Unstable from build defaults

This commit goes through the build_defaults.yaml and removes the sid and
unstable entries. Part of the reason for this removal is the lack of
testing the build but still shipping the packages and we already
build against Debian tests.