Tagging: Add initial infrastructure

Fixes bug 3034
Tagging: Add tags for TPs

Fixes bug 3035
Tagging: Use AJAX for adding tags to TP in TP overview

Fixes bug 3071
Tagging: Manage TP tags in project overview

Fixes bug 3036
Tagging: Use AJAX for adding tags to TP in project overview

Fixes bug 3065