(#20) Update submodules

- Fix code for the updated stomp_connection_new() prototype.

- Use graphite_send_metric() and drop stats_send_metric() which inspired it.
(#20) Add function to merge strings containing sigil-prefixed substrings.

E.g. passing "foo.$1.bar" it will call out for string #1 which may be
a PCRE match or the nth label in a graphite metric name, etc. and merge
them together in a new buffer.
(¢20) Refactor graphite-rewrite.

Uses generic merge_nth_string() instead of pcre_replace().
(#20) Update graphite submodule.
(#20) Add support for dynamic STOMP destinations.

STOMP destinations can now contain $n references to the nth label in a metric.
So for example, if the destination was "/exchange/graphite/$1" and the metric
was "foo.bar.baz", then the STOMP destination would be
"/exchange/graphite/foo".

Metric batching will only batch while the destination is consistent, if it
changes then any batched metrics are flushed first.
(#20) Bump package version.
Tweak RPM spec file.
(#20) Take more care clearing the cached destination.