* init
* Aligned default values on security settings.
* Added validator for security settings.
* Provide default implementation for get members by email.
* Refactored constructor of MemberController.
* Validate on unique member email only when configured to do so.
* Further code tidy and use of DI in constructor.
* Used new constructor in tests.
* Add unit test for modified behaviour.
* Removed validator for security settings (it's not necessary, I got confused with users and members).
* Spelling.
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Co-authored-by: Andy Butland <abutland73@gmail.com>