Add metrics sessions, don't use global event emitter for reporting.
Delete emit.js.
Merge branch 'metrics' into develop
Fix minor logging.
Set the outgoing connection limit to Infinity

The default in Node 0.10 is 5 per host:port, which is a ridiculous
limitation for a proxy.
Updated readme.
Merge branch 'readme' into develop
Fix metrics reporting.
Merge branch 'metrics' into develop
Updated imagetype version (fix #29) and install nasm in travis.
Changed mozjpeg module.

Replaced mozjpeg with mozjpeg-bin.
Now uses mozjpeg 2.0 and do the compilation during install instead of first run.