WIP: #630: Create tests for talkeditor.py following PR #605

Now that PR #605 has been merged, I would like to add some tests for the new functions I created. I will have a better idea of what steps this requires as I start experimenting, but I thought I should create this PR as soon as possible. Ultimately, this should close issue #630 .

Oct. 20, 2014: After some research, I have a slightly better idea of what I need to accomplish. These tasks might change as more information comes along -- I haven't even learned about QtTest yet.

Oct 29, 2014: After further thinking, it might not be worth it to focus on upgrading everything to Pytest just yet. For the time being, I mostly just want to get some tests done. So, I'm putting the Pytest goals on hiatus.

- [ ] Replace the Setup and Teardown functions with a pytest fixture (Hiatus)
- [ ] Adjust existing tests as necessary to conform with pytest style (Hiatus)
- [ ] Refactor talkeditor.py to make it easier to test. In particular, avoid using exec_() method (As of Nov. 3, 2014, it is used in 4 functions)
- [ ] Write test for click_talk
- [ ] Write test for click_add_talk
- [ ] Write test for show_save_prompt
Since `allFields` is only created for the for-loop, the temporary variable can be skipped by iterating directly over the list.
```python
for field in [self.titleLineEdit, ...]:
```
But because the list is so long, this won't work well with our max line length limit of 120 chars.

There's a lot of repeated patterns in the list elements, so we can take advantage of that to shorten the list.
```python
for field in ['titleLineEdit', ...]:
    getattr(self, field).setEnabled(bool)
```

Still some repeated patterns that we can move out of the list.
```python
for field in ['titleLine', 'presenterLine', 'categoryLine', 'eventLine', 'roomLine', 'date', 'startTime', 'endTime', 'descriptionText']:
    getattr(self, field + 'Edit').setEnabled(bool)
```
Unfortunately it's still over the max length limit :(

But we can still shave off a few characters.
```python
for field in 'titleLine presenterLine categoryLine eventLine roomLine date startTime endTime descriptionText'.split():
    getattr(self, field + 'Edit').setEnabled(bool)
```
That's under 120 chars, but indented it won't be. At this point it can be made into a multi-line string by triple-quoting it, but then you might as well keep it as a multi-line list.

Anyway, `allFields` should be `all_fields` according to our styleguide, but it might as well be simplified to `fields`.