Omit migrations from code coverage reports.

Also omit portal and terrain, which are used for the lettuce testing framework.

cms/.coveragerc

@@ -2,7 +2,7 @@
 [run]
 data_file = reports/cms/.coverage
 source = cms,common/djangoapps
-omit = cms/envs/*, cms/manage.py
+omit = cms/envs/*, cms/manage.py, common/djangoapps/*/migrations/*
 
 [report]
 ignore_errors = True

lms/.coveragerc

@@ -2,7 +2,7 @@
 [run]
 data_file = reports/lms/.coverage
 source = lms,common/djangoapps
-omit = lms/envs/*
+omit = lms/envs/*, lms/djangoapps/portal/*, lms/djangoapps/terrain/*, common/djangoapps/*/migrations/*
 
 [report]
 ignore_errors = True