This runs through all of global-requirements.txt and looks at the
release history of all components over the last N days, returning the
released list. This is helpful in unexplained gate breaks to at least
look for candidate libraries.
Fleshed out some docs to explain intent for future consumers /
modifiers of this script.
Change-Id: I5880a1d7f0a6063a45f7533319fed1ff56057144
0c2eef0a4f