RR: add shared field for projects
RR: allow anonymous user to view public projects
RR: add default  json data for project arbitrary metadata
RR: remove unnecessary assert
Merge pull request #397 from onaio/319-make-public-projects-accessible

Make public projects accessible
RR: add require-auth field to xform model
RR:  list orgs for which user has permissions, closes #398
RR: hide private forms and prevent submission from non-owners
RR: test submission to a private form by non-owner is forbidden.