allow jenkins-slave to run "mock" on Red Hat

Create a new redhat::mock recipe, and add it to all the Red Hat-based
recipes. This will permit us to use mock to build packages on the
Red Hat-based Jenkins slaves.

Signed-off-by: Ken Dreyer <kdreyer@redhat.com>
Merge pull request #1 from ktdreyer/redhat-mock

allow jenkins-slave to run "mock" on Red Hat