Implement Profile Settings

🚀 Feature Proposal

• As a user, I want to have the possibility to change my avatar.
• As a user, I want to have the possibility to change my title.

Motivation

Whenever a new avatar or a new title is available/unlocked the user might want to set it as it shows his/her upgrage to other users.

Technical Details

Requires #12 (closed) and #13.

Example

After playing a lot of questions in the "Math" question pool the user unlocks the "MathHero" title. Now he/she wanrts to set it as his/her current title.