gpg-agent plugin service check changed

Running on OsX 10.8

When using gpg-agent plugin, found numerous instances of gpg-agent running on my system, growing linearly with time.  Found existing check for running services is calling a deprecated command.  The gpg-agent -q command appears to check for the same state.

![image](https://f.cloud.github.com/assets/191587/1030794/102631ee-0ec5-11e3-800b-90c74a83da1c.png)