Upgrade from 0.2 to 0.3.

<ChangeLog>

*) Change: the Go package name changed to "nginx/unit".

*) Change: in the "limits.timeout" application option: application start

time and time in queue now are not accounted.

*) Feature: the "limits.requests" application option.

*) Feature: application request processing latency optimization.

*) Feature: HTTP keep-alive connections support.

*) Feature: the "home" Python virtual environment configuration option.

*) Feature: Python atexit hook support.

*) Feature: various Go package improvements.

*) Bugfix: various crashes fixed.

</ChangeLog>