boss_session: mnesia initialization improved;

When the `session_adapter` is set to `mnesia`, the Mnesia
schema was not created automatically. This is to fix it
by adding the `ensure_schema` function.

Note that it has not been tested in distributed environment
yet so we expect the `ensure_schema` may become a bit more
complex in the future.

Additionaly, the timeout for `wait_for_tables` was
increased from 20ms to 1000ms because 20 was not enough
at least in our testing environment.
Fix controller adapters before_filters bug

Obviously, the `Info` variable from the function header
didn't match the result of `before_`.

`Other`, the default case branch, was removed to follow
"let it crash" approach.
Fix ctrl adapters incompatible structures matching

`AuthInfo` and `RequestContext` are not "compatible"
so it makes no sense to use `RequestContext` as a default
value for `AuthInfo` if it is not contained in `RequestInfo`
itself.
Pass a new _req template variable

Provide all the templates with a new `_req` variable
that holds the original web request so that template
can use query and post params directly.

There are situations where it is much more straightforward
than to pass the specific parameters via controller
all the time again and again, across the whole application.
Merge branch 'mnesia_cache' of http://github.com/ztmr/ChicagoBoss into stable
Merge branch 'ztmr/ctrl_filter_fix' into stable
Merge branch 'ztmr/dtl_req_var' into stable