Add a threshold/minimum value to report before converting results to 0

So I've been using the ganglia reporter to send a bunch of captured metrics.  However, I see a bunch of errors in my syslog on the gmetad server that is capturing /creating the RRDs for these metrics.  The errors look like this:
 RRD_update (/var/lib/ganglia/test/rrds/Cloud ETL/ignite-small34.ignite.net/packet.interaction.m15_rate.rrd): /var/lib/ganglia/test/rrds/Cloud ETL/ignite-small34.ignite.net/packet.interaction.m15_rate.rrd: converting '4.44659081257E-313' to float: Numerical result out of range

So in an effort to prevent downstream RRD underflow, I am proposing this small change to put a 'floor' on the smallest value that will be sent...converting smaller values to 0.0