Clear key conflict before replaying it

Don't save the change until we successfully process the message, but
make it first so that the user sees the error disappear when the new key
is accepted.

// FREEBIE

js/models/messages.js

@@ -233,6 +233,7 @@
         resolveConflict: function(number) {
             var error = this.getKeyConflict(number);
             if (error) {
+                this.removeConflictFor(number);
                 var promise = new textsecure.ReplayableError(error).replay();
                 if (this.isIncoming()) {
                     promise = promise.then(function(dataMessage) {