Pluggable InputTypes use edxmako.paths.add_lookup to inject new
mako template directories. Those were getting clobbered by microsites
(and by theming), which were completely rebuilding the mako template
lookup list from scratch.
This commit switches those two features to use the same add_lookup
function as pluggable InputTypes.
[LMS-2489]
third_party_auth contains a working settings mechanism, the start of the provider interface + 3 implementations (Google, Mozilla Persona, LinkedIn), and a stub for the auth pipeline. Modified existing lms settings files to use but deactivate the module.
There's no need to display a traceback for every failed content load,
the comment before the log line even says so.
The exceptions shown before tests are run are because of the eager
initialization of the modulestores. They don't need to be initialized
then, that just speeds the responsiveness of servers. Putting off the
initialization means they get inited as needed, and the log lines get
