[PATCH] support arguments in callout exec

here is argument support for CALLOUT exec:

CALLOUT, PROGRAM="/bin/echo -n xxx", BUS="usb", ID="xxx", NAME="webcam%n"

results in:

Nov 20 02:35:20 pim udev[30422]: get_major_minor: found major = 81, minor = 0
Nov 20 02:35:20 pim udev[30422]: exec_callout: callout to /bin/echo -n xxx
Nov 20 02:35:20 pim udev[30422]: exec_callout: callout returned 'xxx'
Nov 20 02:35:20 pim udev[30422]: get_attr: kernel number appended: 0

The feature is really nice, but the maximum argument count is hard coded to 8.