setTrusted() -> setApproved() to dismiss the five-second warning

This change makes sense, since there was already a reference in the code
to the then-nonexistent setApproved()!

FREEBIE

js/views/message_detail_view.js

@@ -52,7 +52,7 @@
                 return this.model.isUntrusted();
             }.bind(this)).then(function(untrusted) {
                 if (untrusted) {
-                    return this.model.setTrusted();
+                    return this.model.setApproved();
                 }
             }.bind(this)).then(function() {
                 this.message.resend(this.outgoingKeyError.number);