Having pid file would be nice.

``` python
         if(GitAutoDeploy.daemon):
             pid = os.fork()
             if(pid != 0):
+                with open('/var/run/GitAutoDeploy.pid', 'w') as f:
+                    f.write(str(pid))
+                    f.close()
                 sys.exit()
             os.setsid()

```
