Test implementation of gmetric sink.
Fix some bugs.
Merge pull request #47 from ealekseev/gmetric

Gmetric sync to send metrics to ganglia.
Document the available sinks
Added support for key prefix configuration.
Adding histogram alias of timers. Fixes #48.
Update README.md
Update README.md

Readme fix
Some boring stuff.
Removed the branching in stream_formatter.
Using prefixes by default is enabled again.
Fixed default prefix names.
Small fixes.
Update README.md
Fixed possible memory leak on config reload (can we do it? >_>)
No more callocs. Also fixed some whitespace.
More formatting fixes
Assert for asprintf.
Fixed README misprint
Fixed comparison of double variables and float constants.