Add schema.org/SearchAction markup for Google Sitelinks support

Add schema.org/SearchAction markup for Google Sitelinks for sites which Google deems worthy of offering the feature.
Implemented only for home page, as per Google instructions at https://developers.google.com/webmasters/richsnippets/sitelinkssearch
fix newline at end of file
Merge pull request #166 from drbyte/sitelinks

Add schema.org/SearchAction markup for Google Sitelinks support