Summary: Support selecion session/otk data store. Add redis as data store. Allow admin to select the backend data store. Compatibility matrix: main\/ session>| anydbm | sqlite | redis | mysql | postgresql | anydbm | D | | X | | | sqlite | X | D | X | | | mysql | | | | D | | postgresql | | | | | D | --------------------------------------------------------------+ D - default if unconfigured, X - compatible choice DETAILS roundup/configuration.py: add config.ini section sessiondb with settings: backend and redis_url. CHANGES.txt, doc/admin_guide.txt, doc/installation.txt, doc/upgrading.txt: doc on config of session db and redis. Plus some other fixes: admin - clarified why we do not drop __words and __testids table in native-fts conversion. TYpo fix. upgrading - doc how you can keep using anydbm for session data with sqlite. Fix dupe sentence in an upgrading config.ini section. roundup/backends/back_anydbm.py, roundup/backends/back_sqlite.py: code to support redis, redis/anydbm backends respectively. roundup/backends/sessions_redis.py new storage backend for redis. roundup/rest.py, roundup/cgi/actions.py, roundup/cgi/templating.py redis uses a different way of calculating lifetime/timestamp. Since expiration of an item occurred if its timestamp was more than 1 week old, code would calculate: now - 1 week + lifetime. But this results in faster expiration in redis if used for lifetime/timestamp. Convert code to use the lifetime() method in BasicDatabase that generates the right timestamp for each backend. test/session_common.py: added tests for more cases, get without default, getall non-existing key etc. timestamp test changed to use new self.get_ts which is overridden in other tests. Test that datatypes survive storage. test/test_redis_session.py: test redis session store with sqlite and anydbm primary databases test/test_anydbm.py, test/test_sqlite.py add test to make sure the databases are properly set up sqlite - add test cases where anydbm is used as datastore anydbm - remove updateTimestamp override add get_ts(). test/test_config.py tests on redis_url and compatibility on choice of sessiondb backend .travis.yml: add redis db and redis-py

Debugging Aids
--------------

Try turning on logging of DEBUG level messages. This may be done a number
of ways, depending on what it is you're testing:

1. If you're testing the database unit tests, then set the environment
   variable ``LOGGING_LEVEL=DEBUG``. This may be done like so:

    LOGGING_LEVEL=DEBUG python -m pytest test/

   This variable replaces the older HYPERDBDEBUG environment var.

2. If you're testing a particular tracker, then set the logging level in
   your tracker's ``config.ini``.

SENDMAILDEBUG
=============

Set to a filename and roundup will write each email message
that it sends to that file instead to the internet. 
This environment variable is independent of the python -O flag.