Support for google site link search.

#### What's this PR do?
Support for those embedded search boxes inside google search results.

#### Where should the reviewer start?
Likely reading up on how it all works.

https://developers.google.com/webmasters/richsnippets/sitelinkssearch
#### How should this be manually tested?
I don't think this can be manually tested, as it relies on (according to the docs) to be indexed by Google.
#### What are the relevant tickets?
Fixes #477
#### What gif best describes this PR or how it makes you feel?
![](http://media.tumblr.com/tumblr_lqitiw3NGF1qh2f6w.gif)