add coverage package name option to testr
add coverage package name option to testr

since setup.cfg lists package name as poppycdn, running
coverage failed to generate any data. specify a package
as poppy different from the one in setup.cfg.

Change-Id: Iac721e9df96807b4182e49a6b29a25f0c5b3e0b0

stackforge/poppy,openstack/poppy,openstack/poppy,stackforge/poppy,stackforge/poppy,openstack/poppy