Remove logging of gmetric errors
Make supression of log message configurable
Change value_threshold computation to match doc:
http://sourceforge.net/apps/trac/ganglia/wiki/Gmond%203.1.x%20General%20Configuration#collection_group
Fix to handle metric groups that specify TimeThreshold
Fix a number of bugs in when metrics are announced:
* Always collect and announce metrics on startup.
  This is particularly important for collect_once metrics,
  Which would previously only be announced after the time_threshold.
* Compare against the previous announced value for determining
  whether the threshold is crossed. Without this fix a steadily
  increasing metric that never increased by more than the threshold
  in one collection interval would not be reported again.
* Handle a number of other cases when comparing against a threshold.
  Particularly important for non-numeric metrics, which would always
  cause a badarith exception before.
Don't try to announce undefined metrics
Always trace on exceptions collecting
remove require_otp_vsn
Merge pull request #3 from talko/master

Improvements by @talko