GraphiteHandler sends ntpd.offset value as 0 about diamond HOT 1 OPEN

@sacharv I have encountered this bug too.
I found many collectors didn't specify the precision parameter (it's default value is 0), and when use GraphiteHandler to send metric, the precision will cause this bug, the fractional-part will be dropped.

## The following is copyed from Metric.__repr__ function

# Set the format string
fstring = "%%s %%0.%if %%i\n" % self.precision

# Return formated string
return fstring % (self.path, self.value, self.timestamp)

There are many ways to fix this bug:

• Change the default value of precision (e.g. precision=3)
• Compute the precision dynamically according to the value of metric. e.g.

precision = 0 if value > 50 else 3

• Add precision parameter to all collectors.

@mattrobenolt @kormoc @rtoma @josegonzalez Can you give me some suggestions to fix this bug ?

from diamond.