Adding field requireLogin to following objects:
 - `Conferences` database relation
 - `ConferenceEntity` class (database model entity)
 - `Conference` class (web model entity)

Also updated service tests and unit tests to account for new field.
Merge branch 'no-login-field' of http://github.com/CruGlobal/conf-registration-api into no-login-field
Rename method from getRequireLogin to isRequireLogin for clarity