WIP: Refactor study description

This WIP pull request is breaking up the study description handler in multiple UI modules, as well as breaking up the study handlers file to be hosted on multiple files for easy edition.

I still need to decompose the post of the study handler in multiple post-only handlers that will help to maintain the page.

Feel free to make any comment if you feel that there is something really wrong.
Can be simplified some

```python
if study_title is None:
    to_write = False
elif study_title == old_study_title:    # dont believe the explicit test for old_study_title is necessary
    to_write = True
else:
    to_write = False if Study.exists(study_title) else True

self.write(str(to_write))
```