Add Member model feature to Images API v2

Previously undocumented/missing Image Member feature now implemented.
Fixed reviewer comments - a few minor pep8 issues.

Fixed serialisation and deserialisation issues for the member model
Fixed line continuation and import issues as per reviewer comments.
Made a small refactoring to inline a variable as per reviewer comment.

Fixed the date format issue as per reviewer comment.

Change-Id: I4c5698d72205944d484d90445123d740f98a50da
Merge "Add Member model feature to Images API v2"