(Bug 3376) Add search for support requests

This extends full text Sphinx search to our support system, with respect
for the viewer's privileges.

This requires an update to your sphinx configuration to configure the
new 'dwsupport' index. You will also need to set up a cron job that
runs:

    bin/ljmaint.pl copy_supportlog

After that runs, you need to reindex and rotate the index with Sphinx:

    indexer --rotate dwsupport

That's all.