bugfix: allow bin upper limits to contain decimals

also modify an example to demonstrate

README.md

@@ -57,13 +57,13 @@ ordered non-inclusive upper limits of bins (class intervals).
 (use `inf` to denote infinity; a lower limit of 0 is assumed)
 Each `flushInterval`, statsd will store how many values (absolute frequency)
 fall within each bin (class interval), for all matching metrics.
-First match wins.  examples:
+Examples:
 
 * no histograms for any timer (default): `[]`
 * histogram to only track render durations,
   with unequal class intervals and catchall for outliers:
 
-        [ { metric: 'render', bins: [8, 25, 50, 100, 'inf'] } ]
+        [ { metric: 'render', bins: [ 0.01, 0.1, 1, 10, 'inf'] } ]
 
 * histogram for all timers except 'foo' related,
   with equal class interval and catchall for outliers:
@@ -71,9 +71,13 @@ First match wins.  examples:
         [ { metric: 'foo', bins: [] },
           { metric: '', bins: [ 50, 100, 150, 200, 'inf'] } ]
 
-Note that this is actually more powerful than what's strictly considered
-histograms, as you can make each bin arbitrarily wide if you want to
-(upto infinity), i.e. class intervals of different sizes.
+Note:
+
+* first match for a metric wins.
+* bin upper limits may contain decimals.
+* this is actually more powerful than what's strictly considered
+histograms, as you can make each bin arbitrarily wide,
+i.e. class intervals of different sizes.
 
 Sampling
 --------

backends/graphite.js

@@ -142,7 +142,8 @@ var flush_stats = function graphite_flush(ts, metrics) {
         for (; i < count && (bins[bin_i] == 'inf' || values[i] < bins[bin_i]); i++) {
           freq += 1;
         }
-        message += 'stats.timers.' + key + '.bin_' + bins[bin_i] + ' ' + freq  + ' ' + ts + "\n";
+        bin_name = ('bin_' + bins[bin_i]).replace('.','_');
+        message += 'stats.timers.' + key + '.' + bin_name + ' ' + freq  + ' ' + ts + "\n";
       }
 
       statString += message;

exampleConfig.js

@@ -59,7 +59,7 @@ Optional Variables:
                     First match wins.  examples:
                     * histogram to only track render durations, with unequal
                       class intervals and catchall for outliers:
-                      [ { metric: 'render', bins: [8, 25, 50, 100, 'inf'] } ]
+                      [ { metric: 'render', bins: [ 0.01, 0.1, 1, 10, 'inf'] } ]
                     * histogram for all timers except 'foo' related,
                       equal class interval and catchall for outliers:
                      [ { metric: 'foo', bins: [] },