Allow users to create public labels

[mdpiper]

This could become messy, but I think it's the right way to deal with the idea of projects in WMT.

Some thoughts:

• Will users be able to delete public labels? (What if I make a typo when creating a label? What if someone spams us and makes a gazillion labels?)
• Will only the owner be able to delete a label they've made? (Perhaps make a csdms@colorado.edu superuser account.)
• Maybe make a list of usernames that are authorized to create/delete public labels and store them in the config.json file?