ME: added 'metadata' fields to user profile model and serializer
ME: added tests to check if profiles have metadata attribute
ME: added metadata fields to the model and the serializer
ME: added a migration file to update the user profile model
ME: added metadata field to user_profile_data return value
ME: refactored test_project_get_starred_by test
ME: fixed failing tests by refactoring code
Merge pull request #660 from onaio/572-add-metadata-field-to-user-profiles

572 add metadata field to user profiles