Prettifying connection hook interface.

Now connection object accepts three hooks: `connected`, `disconnected` and `message`.
Make HookManager outer class.
Todo about ipv6 support added.
Synchrony namespace appended.
Missed logger definition.
Removed duplicate log message.
Now locator endpoint can be specified for services.

Also added another log message.
Lock on dependency versions.
Actually using locator settings.
Merge branch 'master' of github.com:cocaine/cocaine-framework-ruby