Revert "Merge branch 'devel' of https://github.com/otavanopisto/muikku.git into"

This reverts commit 2b662b9534d1f345fc2880350813cdcddad7d526, reversing
changes made to 900b9c8ddd2c26e66fe55f097502ca390b40706e.
Revert " - Fixed User check in email change confirmation"

This reverts commit 900b9c8ddd2c26e66fe55f097502ca390b40706e.
Revert " - User Email Change plugin"

This reverts commit f2b5909ba80b0bac953fc07e3092be6ee1767b4e.