AMY release v1.11.3

This release is intended to upgrade AMY's dependencies and the source code accordingly to the changes required by newer versions of the dependencies.

Bug fixes

• Aditya had started, and Piotr finished fixing an annoying lack of redirection from '/' to the dashboard ('/workshops/'),
• Piotr fixed a rare bug appearing when merging two persons, a database constraint (usernames or Twitter usernames or Github usernames) could be violated,
• Andy provided a fix for fake database generation.

New features

• Jonah added two more badges to AMY that correspond to mentor trainings,
• Piotr upgraded AMY's dependencies since they were long overdue.