Update from 1.10.0 to 1.11.0.

Please read the following email to better understand how to use
new nginx unit features,
http://mailman.nginx.org/pipermail/unit/2019-September/000167.html

<ChangeLog>

*) Feature: basic support for serving static files.

*) Feature: isolation of application processes with Linux namespaces.

*) Feature: built-in WebSocket server implementation for Java Servlet

Containers.

*) Feature: direct addressing of API configuration options containing

slashes "/" using URI encoding (%2F).

*) Bugfix: segmentation fault might have occurred in Go applications

under high load.

*) Bugfix: WebSocket support was broken if Unit was built with some

linkers other than GNU ld (e.g. gold or LLD).

</ChangeLog>