changes to make image membership tests pass

Needed by
Change-Id: I270ad24c4d82bc31fb5b07ea05bc84458844143e

 - introduced MemberList model
 - added remote image url properties to config
 - rebased with dependancy
 - implemented member model deserialization
 - updated relevant images client calls
 - fixed outdated/incorrect import user.py
 - fixed tenants deserialization

Change-Id: I4a892c001ab312000ce59da59c73d3a75316963e