LP#1369169: Add websockets section to the OpenSRF README

LP#1369169: Add websockets section to the OpenSRF README

Remove the separate README.websockets and move the contents into the primary
OpenSRF README document so that all steps are in one place.

Additional edits to the websockets instructions to detail differences made
between Ubuntu 14.04 Trusty and Debian / Ubuntu 12.04 Precise. More edits
may be necessary for Debian Jessie later?

Also, create a separate config file for Apache 2.4 that is copied into place
for Ubuntu Trusty and potentially other systems that will need it.

Signed-off-by: Ben Shum <bshum@biblio.org>