Create pick-a-license frontend

[iameli]

I want people to pick a license for their stream's content before they go live. This is so, going forward, we can really easily implement folks re-broadcasting others streams in a legally coherent way.

It'll basically be this thing from the Creative Commons site, just made more specific for Streamplace content.

It should result in these licenses: https://en.wikipedia.org/wiki/Creative_Commons_license#Seven_regularly_used_licenses

Plus an "all rights reserved" license if you don't want to put any kind of CC license on your work. But it should be at the bottom.