Labels and Duplicate api.py integrations about wekan

[xet7]

@xator91

For duplicate board, you can find related code by searching wekan code directory:

cd wekan

./find.sh duplicate

For example, if that function is at models directory, you can look at other models code how to add new REST API.

For labels, you can also find related code with:

./find.sh label

But I'm not sure what you mean with global, it depends where it is useful to have labels. For example, should there be labels added at Admin Panel / People / Teams, so everyone at that team should have that label at all boards, where team is member of that board.