Added tests for `parse_timestmp` of `djblets.log.views` to address missing test cases

Review Request #9504 — Created Jan. 20, 2018 and updated — Latest diff uploaded




Added tests for djblets.log.views for testing the parse_timestamp

The included tests try the following cases with provided timestamp
format string:
- Empty String of '' being passed
- A string containing something other than a date ('jibberish')
- An invalid date where the month is out of bounds
('1990-55-09 22:11:30')
- A valid date input string ('1990-01-01 20:20:20')

Based most of this behavior off how parse_timestamp behaved in the
interpreter with various inputs. To be more accurate with testing
would require the default implementation for time and datetime,
which mightbe something to be considered with future changes to
python versions however but isn't required for
the scope of this project.

I ran ./tests/runtests djblets.log.tests and
./tests/runtests djblets.log and both pass along with
all other test cases.