remove swiftclient/openstack/common/* in the .coveragerc
remove swiftclient/openstack/common/* in the .coveragerc

There is no swiftclient/openstack/common/* in python-swiftclient.
Therefore, I remove "omit=swiftclient/openstack/common/*"
in the .coveragerc.

Change-Id: Ibf4e4e499cb5538fcd8b1680285294c8a09ad401

openstack/python-swiftclient,sohonetlabs/python-swiftclient,openstack/python-swiftclient,sohonetlabs/python-swiftclient