Fix caching pages

I wanted to use memcached and I followed instructions from this page:
[API controller](http://www.chicagoboss.org/api-controller.html),
but it gave me an error.

I found out, that in `boss_controller_adapter_mod`, `RequestContext` doesn't have
`action` and `tokens` keys and that causes the error.

It was due to a typo in `boss_web_controller_render`,
Instead of `RequestContext3`, there was `RequestContext` passed to `apply_middle_filters`.
Docs state, that request context always has `action` and `tokens` fields
and this is fixed by first commit.

But after that I got `Action returned an invalid return {cached_page,{ok,"HELLO, WORLD!",[]}}`
I've added case clause for cached page in second commit, but I am not sure,
if this is right way to fix that, because those data are passed to `render_view`
and I think cached pages should be rendered immediately.