Enable search module by default

I support that. We need to refactor the Search API to be able to switch more easily to solr or xapian, but that's another issue, one we can probably tackle in the timeframe we have.

This is blocking #497804: [meta] Search entities (nodes, terms, etc.) within the administrative interface, so tagging as d7ux.

Hm. I've committed this. But I'll strongly warn that unless there is follow-up work done, this is going to be every new user's first steps in Drupal:

Step 1: Create some content.
Step 2: Search for it.
Step 3: Post a support request on the forums, since the search didn't find anything.

Since there is no step 0: Set up cron.

If that continues to be the default UX, we'll have to back this out before code freeze.

Wow. Who knew that such a sweet, harmless looking patch could cause a failure in our test suite? ;) http://testing.drupal.org/pifr/file/1/8853

I had to roll this back.

Ok. Now that #504016: Remove stupid assertion is in, trying this patch again. May we all pray that testing bot has mercy on our soul. ;)