Clear old key conflict errors after failed replay

If the replay failed due to a bad mac or other decryption error for some
other reason we still want to clear the conflict. If it failed because
it's still in conflict then the newly returned error will reflect that
and be saved.

// FREEBIE

js/models/messages.js

@@ -246,6 +246,7 @@
                     }.bind(this));
                 }
                 promise.catch(function(e) {
+                    this.removeConflictFor(number);
                     this.saveErrors(e);
                 }.bind(this));