Small fixes

Small fixes
Fixed email filtering

SD-131 : Wrong hint for incorrect e-mail

Fixed email filtering.
Removed the need to target a model

SD-42 : As user I want to change my password

Removed the need to target a model for accessible path in
order to allow other methods.
Merge pull request #128 from mugurrus/apy-8-implement-x-filter

SD-88 : Implement validators for users
Fixed

SD-133 : Delete doesn't work

Fixed, a foreign key cascade forgeten.
SD-88 : Implement validators for users