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
I put at the end of `enable_input_fields` and `disable_input_fields` to replace the respective chunks of code that look like this (with `True` for `enable_input_fields` and `False` for `disable_input_fields`):

`self.titleLineEdit.setEnabled(True)
self.presenterLineEdit.setEnabled(True)
self.categoryLineEdit.setEnabled(True)
self.eventLineEdit.setEnabled(True)
self.roomLineEdit.setEnabled(True)
self.dateEdit.setEnabled(True)
self.startTimeEdit.setEnabled(True)
self.endTimeEdit.setEnabled(True)
self.descriptionTextEdit.setEnabled(True)`