More configurable coercion

[ikitommi]

replace implementation (not the contract) of default coercion. in compojure.api.middleware:

• remove default-coercion-matchers
• use create-coercion & default-coercion-options instead for more fine grained access, uses format information prodived by Muuntaja to get format-level coercion.
• BREAKING new default coercion rules:

Format	Request	Response
application/json	json-coercion-matcher	validate
application/edn	json-coercion-matcher	validate
application/msgpack	json-coercion-matcher	validate
application/x-yaml	json-coercion-matcher	validate
application/transit+json	validate	validate
application/transit+msgpack	validate	validate

default options (updated):

(def default-coercion-options
  {:body {:default (constantly nil)
          :formats {"application/json" json-coercion-matcher
                    "application/msgpack" json-coercion-matcher
                    "application/x-yaml" json-coercion-matcher}}
   :string string-coercion-matcher
   :response {:default (constantly nil)
              :formats {}}})

to create a valid coercion (for api or to routes):

;; create (with defaults)
(mw/create-coercion)
(mw/create-coercion mw/default-coercion-options)

;; no response coercion
(mw/create-coercion (dissoc mw/default-coercion-options :response)

;; disable all coercion
nil
(mw/create-coercion nil)

Why? More correct behaviour for EDN & Transit, easy to add own custom rules based on formats.

See #266

[ikitommi]

might be a reason to bump the version to 2.0 if this get's merged.