Making form consistent for required/optional fields (Bug #898470)

Change-Id: I87d1d4fd7d8c305f0cdd0623f1d9370bda278bd5
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>

htdocs/account/institutions.php

@@ -196,6 +196,7 @@ if (!empty($institutions) &&
                 'collapseifoneoption' => false,
                 'options' => $options,
                 'defaultvalue' => key($options),
+                'rules'        => array( 'required' => true ),
              ),
             'studentid' => array(
                 'type'         => 'text',

htdocs/lang/en.utf8/mahara.php

@@ -595,7 +595,7 @@ $string['confirminvitation'] = 'Confirm invitation';
 $string['joininstitution'] = 'Join institution';
 $string['decline'] = 'Decline';
 $string['requestmembershipofaninstitution'] = 'Request membership of an institution';
-$string['optionalinstitutionid'] = 'Institution ID (optional)';
+$string['optionalinstitutionid'] = 'Institution ID';
 $string['institutionmemberconfirmsubject'] = 'Institution membership confirmation';
 $string['institutionmemberconfirmmessage'] = 'You have been added as a member of %s.';
 $string['institutionmemberrejectsubject'] = 'Institution membership request declined';