Handle case insensitive CEST properties

Summary:
Allow string comparison in a case-insensitive manner

The properties of the given new revision .json-files are different
to the CEST properties of new CEST data when it comes to
case sensitivity.
Allowing a case-insensitive string comparison helps to overcome
the problem of not correctly matching the properties.

Test Plan: manual testing

Reviewers: floca

Reviewed By: floca

Subscribers: floca, kalali

Maniphest Tasks: T28958

Differential Revision: https://phabricator.mitk.org/D592