Add support for replacing tags in <head>

Add ability to mark _head_ tags with data-turbolinks-replace.

This will remove the tag on page:change and replace it with the new version from the freshly fetched page.

### Example use cases:

* When session storing csrf-token might expire between page change, making the _meta_ tag invalid.
* Could be used in lieu of data-turbolinks-track to replace CSS instead of doing a full page reload.