Introduce .coveragerc

We don't need the result of tempest/tests/* and tempest/openstack/*
coverage. This commit omits it with introducing .coveragerc.

Partially implements bp unit-tests

Change-Id: I0465d916e195e3d340dece24ac7b01a0fc13e5c1
diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 0000000..c9b6467
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,4 @@
+[run]
+branch = True
+source = tempest
+omit = tempest/tests/*,tempest/openstack/*