Fixed presentation fixture and while loop usage.
Removed get_events from database module because it was only used in the
test module.

Altered the update_presentation method in the database module to be more
consistent with the insert_presentation's method of preparing database queries.

Removed string docs from the test_database module since they were reiteratings
of the function names. One string doc was converted into a comment because it
is an assumption about the database state.

Some of the code that got the first record_id from the database was refactored
from the test_database module because of the test_first_talk_id test method.