Fix #395 Talk Editor Redesign

Complete Talk Editor Redesign. Database schema was affected with 2
changes:

    - Level renamed to Category
    - DateTime is now 2 separate fields Date and Time

Issue: #331
Change-Id: Ia6635dcc72aba8b263b2ec4e7874ae706c35e442
Fix Schema Upgrade code

Schemas are now versioned and used when creating new tables. The table
create methods itself will default to the latest schema versions so they
can be used without code changes.

If the presentations table is being creating for the first time. The
upgrade function will no longer need to run. This is achieved by setting
the DB version immediately.

Fixed the default talk to not be blank.

Change-Id: Ibdf9b9b28156ef4dafeefe73ef27124fb0cd5e57
Fix PEP8 errors

Change-Id: Iceef4af7ade0866d2fb2bd6340a1389c3a1c9984
Remove unittests that are no longer valid

Change-Id: Ied7ba5455a299ad93e908bce7f1b56dc554a30b8