add REST documentation
move REST models to separate file
add REST models from common module
convert from body parameter to form parameters
convert body parameter to form parameters
clarify return description; remove body params
follow up on review
more follow up
more followup
more followup
more followup
more followup
more follow up
remove extraneous parameter
move picture info to principals module
correct start token
clarify signed download
separate documentation for content types
make form params arrays when appropriate
add required doc