LP#1391248: Fix NameVirtualHost warnings in websockets apache2.conf

For the websockets configuration, the sample apache2.conf for Apache 2.4 (i.e.
Ubuntu 14.04, etc.) contains NameVirtualHost entries that are no longer
needed.

When starting apache2-websockets, you may see warnings like:

AH00548: NameVirtualHost has no effect and will be removed in the next
release /etc/apache2-websockets/apache2.conf:53

Remove the NameVirtualHost entries and these warnings go away.

Signed-off-by: Ben Shum <bshum@biblio.org>
Signed-off-by: Bill Erickson <berickxx@gmail.com>