Upgrade from 1.4 to 1.5.

<ChangeLog>

*) Change: the "type" of application object for Go was changed to

"external".

*) Feature: initial version of Node.js package with basic HTTP

request-response support.

*) Feature: compatibility with LibreSSL.

*) Feature: --libdir and --incdir ./configure options to install libunit

headers and static library.

*) Bugfix: connection might be closed prematurely while sending

response; the bug had appeared in 1.3.

*) Bugfix: application processes might have stopped handling requests,

producing "last message send failed: Resource temporarily
unavailable" alerts in log; the bug had appeared in 1.4.

*) Bugfix: Go applications didn't work when Unit was built with musl C

library.

</ChangeLog>