Materia v6.0.0 "Ramuh"

Note: this release includes 2x database migrations.

• Sanitizes widget title when exporting play data (#1235)
• Rewords "spoof" to "mock" in tests (#1141)
• Collaboration access level now set to a default value instead of blank (#1158)
• Fixes to long title styling in LTI widget selection (#1129)
• Modest additions to admin page (#1146)
• Relocates logged in user to right side of header (#1214)
• Adds export option for referrer URLs (#176)
• Guide page will only display tabs for existing guides (player/creator) (#1249)
• Adds clarifying information to Export Options modal concerning LTI launches (#1216)
• Support for participation score logging (#1217)
• Removes Group field for widgets (#1157