change ssprintf to asprintf

change ssprintf to asprintf
back out change at line 225 in r1.4
  (values were mismatched to format string, so output was nonsense)
  (I left a comment showing a construct that should work, but it fails for PHBs:
    if my disk gets nearly full, they want 'CRITICAL - 99%' not 'CRITICAL - Gauge32: 99')
  (If someine has a rationale for the change, maybe it could be done as an option? - it seems
    fairly clear that the Web display should be sensible to PHBs so long as there's no real loss)

git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@143 f882894a-f735-0410-b71e-b25c423dba1c