Handle identity key change errors on encrypt

We need to capture key change errors from the protocol library when we call
encrypt. Previously we would only see these on session init.

// FREEBIE

js/libtextsecure.js

@@ -38908,6 +38908,10 @@ OutgoingMessage.prototype = {
                             this.registerError(number, "Failed to reload device keys", error);
                         }.bind(this));
                 }.bind(this));
+            } else if (error.message === "Identity key changed") {
+                error = new textsecure.OutgoingIdentityKeyError(
+                    number, this.message.toArrayBuffer(), this.timestamp);
+                this.registerError(number, "Identity key changed", error);
             } else {
                 this.registerError(number, "Failed to create or send message", error);
             }