Merge branch 'develop'

* new Extension API.
* change Strategy interface.

* add middleware function.
* remove Typeable restriction from Path/Query class.
* remove unused Functor restriction.

* add Optional Strategy, (=?!:) query fetcher.
* add accept filter.
* add Path/Query instances to Day.

clientsession: add sessionTimeoutAction option
update CHANGELOG
Merge branch 'develop'

* fix not accept in multi Accept header.
* add greedy path capture('\*\*').
* add switchQuery filter.
* add Heroku module.
* add google analytics support to API documentation.

* change interface.
* fix bug which immediately finalize.
* deprecate preAction.
* Category initializer only ghc-7.8+.

* apiary-mongoDB
* apiary-memcached