This is for easy programmatic access to the tier name.

* `auto_increment_insert` updates
* `auto_increment_update` updates
* minor visual tweaks
* enable/disable LVAlert via environment variable
* upstream package updates
* bug fixes and performance improvements

Settings have been reorganized and how different parameters are
determined has been reworked to be compatible with both a Puppet-based
VM deployment and a containerized deployment

Add django-user-sessions package for more easily managing sessions
and correlating them with user accounts.

silk was slowing things quite a bit so we won't use it by default,
even in development instances.

Rename config/settings/test.py -> config/settings/dev.py to prevent
the file from being picked up by the test runner during unit testing.

Updated from Django 1.11.5 to Django 1.11.14. Updated 3rd party
packages so that all of them have version requirements in
requirements.txt.  Also updated most of these packages to use the
newest versions.  A specific update to the twilio package required
some changes for how we determine the 'from' phone number. Also
alphabetized the packages in this file.  Finally, added the very
useful django-silk debugger/profiler.

django-extensions was just in the test settings before (i.e., not
deployed on production), but it is pretty nice and useful, so we
are moving it into the base settings so that it can be used
everywhere!