gerrit - use apache::site

use the newer apache::site method rather
than a file{} resource and have proper
symlinks again

currently, due to refactoring, it looks like this:

ytterbium:/etc/apache2/sites-enabled# file gerrit.wikimedia.org
gerrit.wikimedia.org: ASCII English text, with very long lines

ytterbium:/etc/apache2/sites-available# file gerrit.wikimedia.org
gerrit.wikimedia.org: ASCII English text

ytterbium:/etc/apache2/sites-available#
if diff -q gerrit.wikimedia.org ../sites-enabled/gerrit.wikimedia.org;
then echo "2 files with different content, confusing"; fi

Files gerrit.wikimedia.org and ../sites-enabled/gerrit.wikimedia.org differ

Change-Id: Iaacd0dcd9bed12afcfe84c02e59cfd7ec88f9eaa
Merge "gerrit - use apache::site" into production