Log cms_verify issues as warnings (not errors).

In general we probably do want to log these types of errors... but
not as ERRORS. I think log Warning messages are probably more
appropriate here since it would be possible to hit this when
expired certs are refreshed...

Fixes LP Bug #1190230.

Change-Id: I0383f7e490ddcdfb31a62cd3760102152a8d16d9
Fix auth_token.py bad signing_dir log message

Fixes bug 1197755

Change-Id: I16152518c354821af6790a6e459f1d8ec09139a0
Flake8 should ignore build folder

This adds 'build' to the exclude list for flake8

Fixes bug 1198329

Change-Id: Ia3688a2fc0334d32d89f04d114242d39bdc25f0e
Merge "Log cms_verify issues as warnings (not errors)."