Bug 1043604: Add global Apache configuration

A new file is added, all-servers.conf, which contains Apache settings
that should be used on all servers. The file is hooked up to our local
environment via Puppet and the WebOps team <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1043604">will ensure that it's also
used on our public servers</a>.

To test, ensure that the ACAO header is set (with a value of <code>*</code>) on all valid URLs except for the URLs of font files.