split up wrap-cookies into request and response fns
separate out response handling of wrap-not-modified

add unit tests for not-modified-response
split up session middleware into response and request
remove unnecessary use, add docs for new public session fns
separate out response for content-type middleware

also add test for :mime-options
separate out response for file-info middleware
separate out flash middleware into request and response
split out head middleware into response and request
separate out request manipulation of keyword-params middleware
separate out request handling from multipart-params middleware
split out request handling of nested_params

also add test for :key-parser option
separate out request handling of params middleware

also make assoc-form-params public as its used in other middleware
separate out request handling of resource middleware
separate out request handling of file middleware
make session middleware consistent with other middleware

*request and *response fns operate on request and response directly
wrap session-request and session-response with cookies fns
avoid passing :session/key in response for cleaner session middleware
add tests to ensure new *response *requests fns remain public
Merge pull request #38 from redinger/middleware-refactoring

Middleware refactoring