Resolves #809 Prevents org admins from removing their admin role

[jdaigneau5]

Closes Issue #809

Summary

Added logic to prevent org admin users from self demoting and removing their own admin role.

Important Changes

error.js

• Added new error notAllowedToSelfDemote with message 'Please have another admin user from your organization change your role.'

org.controller.js

• In updateUser function, changed forEach loop to for...in so returning errors breaks out of function
• Throws notAllowedToSelfDemote when user tries to remove their own admin role

Testing

Steps to manually test updated functionality, if possible

• 1) Create new org with an admin user
• 2) Attempt to remove the admin role from this user, while using that user's credentials