Fixed download link
Minor dark theme fix
More on that theme
Fix broken unit tests
Do not allow non-images that imagemagick supports
Undo test fix that didn't help things
Fix bug with preview image on pasted image data
Resolve naming conflicts with 'mimetypes' module
Added URL -> hash mapping and URL information endpoint.
Fix upload-from-url typo in jdiez's earlier commit
Add more checks around the url caching system
Remove downtime config

[noupdate]
Check for assignment before use
Modify URLFile to choose an extension
Prefer Content-Disposition to Content-Type on URLs
Merged master