This adds a new argument to projects_depsolve and
projects_depsolve_with_size that contains the group list, unfortunately.
I would have prefered adding a function that just returns a list of all
the contents of a group and then add that to what was being passed into
projects_depsolve. However, there does not appear to be any good way to
do that in yum aside from a lot of grubbing around in the comps object,
which I am unwilling to do.
(cherry picked from commit 0259f3564d)
