Notable changes

• REST API:
  • Support tag URI for user id, app id, and activity id.
• Twitter:
  • Better error message when uploading a photo with an unsupported type.
  • Only include original quote tweets, not retweets of them.
  • Skip fetching retweets for protected accounts since the API call always 403s.
• Flickr:
  • Better username detection. Flickr's API is very inconsistent about username vs real name vs path alias. This specifically detects when a user name is probably actually a real name because it has a space.
  • Uploading: detect and handle App Engine's 10MB HTTP request limit.
  • Bug fix in create: handle unicode characters in photo/video description, hashtags, and comment text.
• Atom:
  • Bug fix: escape &s in attachments' text (e.g. quote tweets).