Add disconnect() to Connection, using the CLS protocol command

Signed-off-by: Pedro Melo <melo@simplicidade.org>

lib/AnyEvent/NSQ/Connection.pm

@@ -85,6 +85,21 @@ sub connect {
   return;
 }
 
+sub disconnect {
+  my ($self, $cb) = @_;
+  return unless my $hdl = $self->{handle};
+
+  $hdl->push_write("CLS\012");
+
+  $self->_on_next_success_frame(
+    sub {
+      $cb->($self, @_) if $cb;
+      $self->_force_disconnect;
+    }
+  );
+
+  return;
+}
 
 ## Protocol API