[DEV-1395] Merge branch 'DEV-1411' into DEV-1395
[DEV-1395] Moved livesettings for gravatar to settings.py (effectively disabling gravatar in livesettings).
[DEV-1395] Remove mention of gravatar in alt-text from gravatar template macro.
[DEV-1395] Replace user's get_avatar_url method with a Rover-specific version.
[DEV-1395] Re-enable livesettings for Gravatar.
[DEV-1395] Revert get_avatar_url in favor of get_default_avatar_url on AskbotUser.
[DEV-1395] Remove whitespace to minimize diff.
[askrover] Merge branch 'DEV-1395' into askrover