or param errors to raise invalid data exception. That will cause
those responses to be handled in by errors.py, which will log
the errors.
Set most of schemas to strict mode so that marshmallow will raise
exception rather than checking for errors in return tuple from load.
Added handler to errors.py for marshmallow validation errors.
Droped token as later code to send email invite can generate
timebased url to send to user. That can then be checked
against configurable time threshold for expiry. Therefore
no need to store a token.
