Disabled package is also indicated by enable blank

I just upgraded to 2.1-BETA1 (i386) built on Tue Apr 2 16:18:36 EDT 2013 and noticed that the handling of disabled packages on the service status displays did not work. Packages like bandwidthd and blinkled set "enable" to blank when they are disabled. This does not match the "=== false" test, so they were not considered disabled.
As per Ermal's suggestion, use an empty() test to cover the various possibilities - false, "", 0, "0" etc.