Add ability to edit document titles

[reefdog]

With this PR, users gain the ability to edit titles and descriptions through the document detail page. Titles are required, while descriptions are optional (and can be deleted). Users can close the form without saving; there's currently no warning or confirmation when closing without saving, but that seems okay since we're talking a small amount of info.

While reviewing, pay particular attention to the new API call for editing the document. I believe it checks the user's permissions properly and only allows changing the title and description, but this is obviously a sensitive action so please double-check me!

• [x] Enable editing document title (required)
• [x] Enable editing document description (optional)
• [x] Enable toggling between edit and display
• [x] Improve styling and layout
• [x] Cleanup code

Closes #18

[metasj]

Title editing should allow editing by an admin, in a way that captures who made the last edit. (Uploaders are often not available to clean up their files)

[slifty]

@metasj this PR is in response to issue #18 which explicitly is requesting the ability for uploaders to edit their titles.

What you are describing sounds like a second issue; could you create that, and reference #18.

[metasj]

18 includes "We will also want to be able to bulk update some titles with scripts, for instance those with blank titles and HTML pages with long, unhelpful ones." So no new issue needed I think, but perhaps an additional PR ~

[slifty]

Got it.

Either way it would be appropriate to break that into its own issue since it sounds like #18 was actually a compound issue (had I realized I would have suggested splitting anyway!)