split received data on newlines

As described in https://github.com/b/statsd_spec#metric-types--formats
the format of exported metrics is UTF8 text, with metrics separated by newlines

So this split data on newlines as done in origin statsd implementation:
https://github.com/etsy/statsd/blob/master/stats.js#L175-179
fix tests: _process signature has changed
Merge pull request #11 from bbinet/process-data-newline

Process data separated by newlines
generalize to support more than one sink type backend

support for influxdb backend is on its way
free the memory buffer when we're done with it
factor out timer stats computation in a dedicated function

_compute_timer_stats
add support for influxdb backend
update optionparser doc for influxdb backend
fix _hosts and _urls attributes should be specfic to the instance

(not shared accross all classes instances)
fix failing tests
update readmes