Search docs

Mostly adds docs for search, but a few other things

* Adds search documentation.
* Fixes vagrant memory issues when running tests by creating and enabling a swapfile during provision
* Enforces order of bundle tests from phpunit.xml
* fixed docs styling

If I don't come in next week, this should be deployable to staging now.  But `ayamel-ansible` will need to be updated to add in the setup for elastic-search.  If it works fine in staging, go ahead and merge the search branch into master.  Provision a new machine for search in production and configure/deploy.

For production:

* Start new "search" server that's only configured to run ElasticSearch
* Add config for the `search_index` rabbitmq consumers to run on the task machine.  It think transcoding runs 4 processes, I would start 2 search index processes.

In production just run `fos:elastica:reset` and `fos:elastica:populate` from the task server to populate the index.