refactor!: delete common/lib and related usages

pavement.py

@@ -5,8 +5,6 @@ import os
 # takes precedence over anything else installed in the virtualenv.
 # In local dev, we usually don't need to do this, because Python
 # automatically puts the current working directory on the system path.
-# In Jenkins, however, we have multiple copies of the edx-platform repo,
-# each of which run "pip install -e ." (as part of requirements/edx/local.in)
 # Until we re-run pip install, the other copies of edx-platform could
 # take precedence, leading to some very strange results.
 sys.path.insert(0, os.path.dirname(__file__))