add site search by swiftype

[billryan]

I wrote a site search plugin for gitbook, which can be found in https://github.com/billryan/gitbook-plugin-swiftype. It works well when loading a new page or refreshing the old page, but it does not work for 'page.change' event in Gitbook. Anyone can give a hint?

[billryan]

It seems gitbook backend updated and fixed the page.change event handler.