Changes to Security authorization

* auth.py
    -method auth_field_and_value moved to BasicAuth
    -method auth_field_and_value returns a dict instead of key and value
    -class DummyAuth created, it inherits BasicAuth and implementing a dummy check_auth method that always returns True
* flaskapp.py
    -by default is not auth parameter is received auth is setter to class DummyAuth (to use the original auth_field_and_value method)
*base.py
    -method _datasource_ex in class DataLayer was modified to retrieve the "auth" query from the configured auth class instead of method auth_field_and_value, it allow to configure custom  content based rules for object retrieval (need to fix issue #77 patch)
* common.py
   -modifications to the method resolve_user_restricted_access to
save the values returned from auth.auth_field_and_value as access metadata