Validate array params against list of acceptable values.
Routing methods dsl refactored to get rid of explicit paths parameter
Fixes #791
Specs for Mutually Exclusive and Exactly one of in groups

This adds tests for the `mutually_exclusive` and `exactly_one_of`
behaviour in a param group. References #699.
Documented how to use custom middleware, including ActionDispatch::RemoteIp refs: #648.
add a failing spec for #652 issue
when some provided group param is invalid
Merge pull request #828 from dm1try/add_failing_spec_for_grouped_params_with_provided_type

add a failing spec for #652 issue
Fix: regression, params accummulating.
Merge pull request #834 from dblock/params-bug

Fix: regression, params accumulating.
Remove logging value, improve nested loading performance.