Fix leave group bug

This one's been around since forever, but only manifests when someone
leaves the group and comes back. In that case we fail to reinit their
numberRegistrationId object, which causes a npe when we try to send
send them group messages.

Affected parties must ask their fickle friends to leave/join again.

// FREEBIE

js/libtextsecure.js

@@ -38205,7 +38205,7 @@ axolotlInternal.RecipientRecord = function() {
 
                 var i = group.numbers.indexOf(number);
                 if (i > -1) {
-                    group.numbers.slice(i, 1);
+                    group.numbers.splice(i, 1);
                     delete group.numberRegistrationIds[number];
                     return textsecure.storage.axolotl.putGroup(groupId, group).then(function() {
                         return group.numbers;

libtextsecure/storage/groups.js

@@ -86,7 +86,7 @@
 
                 var i = group.numbers.indexOf(number);
                 if (i > -1) {
-                    group.numbers.slice(i, 1);
+                    group.numbers.splice(i, 1);
                     delete group.numberRegistrationIds[number];
                     return textsecure.storage.axolotl.putGroup(groupId, group).then(function() {
                         return group.numbers;