Users can register on all organizational commonses

[mikethicke]

Registration for each Commons (hc, mla, msu, etc) is controlled by a separate enrollment flow in COmanage. The URLs for these enrollment flows are contained in .env (/srv/www/commons/current/.env). The registration page for each Commons should have a 'Register' button that users can click that will take them to the appropriate enrollment flow as determined by .env.