FIXES DEVELOPER-3538 (lots of url_aliases)

[LightGuard]

See https://issues.jboss.org/browse/DEVELOPER-3538 for more information.

This addresses content pages (note things like video pages and some
resource pages will still always be updated) going forward. They will
not be updated unless the source is newer than what's already within
Drupal.

To mitigate the extraneous aliases we'll need to run the following SQL
on the production database:

CREATE TEMPORARY TABLE tmp_alias
  SELECT pid, source, alias
  FROM url_alias
  WHERE url_alias.pid <> (SELECT MAX(pid)
                          FROM url_alias AS inner_alias
                          WHERE inner_alias.alias = url_alias.alias);

DELETE url_alias
FROM url_alias
INNER JOIN tmp_alias
ON url_alias.pid = tmp_alias.pid

[LightGuard]

The easiest way to test this is to have a Drupal instance up and running that already has data in it from a previous run.

[JBossJenkins]

RHD success

[Dantheman720]

Looks good to me