Description of problem:
When executing "pm-powersave true" it fails with the message:

You do not have write access to /proc/sys/vm/

ls -l for /proc/sys/vm shows:

dr-xr-xr-x 2 root root 0 Jan 16 12:44 vm

however, ls -l within /proc/sys/vm shows e.g;

-rw-r--r-- 1 root root 0 Jan 16 12:47 laptop_mode

So pm-powersave *could* still write to the files if it had the correct check for
being able to write there.

Version-Release number of selected component (if applicable):
pm-utils-0.19-3

How reproducible:
Always

Steps to Reproduce:
1. Run pm-powersave true
2.
3.
  
Actual results:
error: You do not have write access to /proc/sys/vm/

Expected results:
output: **SetLowPower ON


Additional info: