Add coverage to openedx directory

cms/.coveragerc

 # .coveragerc for cms
 [run]
 data_file = reports/cms/.coverage
-source = cms,common/djangoapps
-omit = cms/envs/*, cms/manage.py, common/djangoapps/terrain/*, common/djangoapps/*/migrations/*
+source = cms,common/djangoapps,openedx/core/djangoapps
+omit = cms/envs/*, cms/manage.py, common/djangoapps/terrain/*, common/djangoapps/*/migrations/*, openedx/core/djangoapps/*/migrations/*
 
 [report]
 ignore_errors = True

lms/.coveragerc

 # .coveragerc for lms
 [run]
 data_file = reports/lms/.coverage
-source = lms,common/djangoapps
+source = lms,common/djangoapps,openedx/core/djangoapps
 omit = lms/envs/*, common/djangoapps/terrain/*, common/djangoapps/*/migrations/*, openedx/core/djangoapps/*/migrations/*
 
 [report]

openedx/core/lib/.coveragerc

+# .coveragerc for Open edX core lib
+[run]
+data_file = reports/openedx/core/lib/.coverage
+source = openedx/core/lib
+
+[report]
+ignore_errors = True
+
+[html]
+title = Open edx Core Lib Python Test Coverage Report
+directory = reports/openedx/core/lib/cover
+
+[xml]
+output = reports/openedx/core/lib/coverage.xml