Validate form.
        Return True if Django validates the form, the username obeys the parameters, and passwords match.
        Return False otherwise.

def is_valid(self):
        ''' Validate form.
        Return True if Django validates the form, the username obeys the parameters, and passwords match.
        Return False otherwise.
        '''
        if not super(ProfileRequestForm, self).is_valid():
            return False
        validity = True
        if self.cleaned_data['password'] != self.cleaned_data['confirm_password']:
            form_add_error(self, 'password', "Passwords don't match.")
            form_add_error(self, 'confirm_password', "Passwords don't match.")
            validity = False
        return validity