Add support for reloading the page with a response attribute.

Now, a response with the `reload` attribute will trigger a reload.  The
attribute value should be a boolean, as follows:
```json
{
  "reload": true
}
```

Closes #103.
Add cache.remove and cache.clear as external APIs.
Merge pull request #109 from nicksay/reload

Add support for reloading the page with a response attribute.
Ensure the spf.process API function works.

Add a dedicated function to process a SPF response on the current page outside
of a navigation flow.  Export it as the `spf.process` function.

Closes #108.
Merge pull request #110 from nicksay/process-api-vs-library

Ensure the spf.process API function works.
Scroll elements into view after navigation.

When navigating to a URL with a hash (aka fragment) that references a page
element, scroll the element into view before completing the navigation.  This
means that for a URL such as `/page#element-id`, the `scrollIntoView` function
is called on the referenced element just before the `spfdone` event is fired.

Closes #73.
Merge pull request #111 from nicksay/scroll-into-view

Scroll elements into view after navigation.
Merge pull request #114 from DavidCPhillips/cache-invalidation

Add cache.remove and cache.clear as external APIs.