Allow to use chunked encoding with Hunchentoot

This allows to use chunked encoding with Hunchentoot if a function is
provided as the body value of the reply, and if the header Transfer-Encoding
is set to chunked. The function is then called with the output stream as
argument.

Signed-off-by: Julien Danjou <julien@danjou.info>
Merge pull request #56 from jd/jd/chunked

Allow to use chunked encoding with Hunchentoot
clack.handler shouldn't catch all conditions.
added a keyword argument `:allow-head-p' to `clack.util.route:match'. if it is T, clack.util.route:match treat a HEAD request as like GET one.
changed :allow-head-p to :allow-head.
handlers to support for unsigned octet vector
Merge pull request #57 from snmsts/handle-octets

handlers to support for unsigned octet vector
replaced documentation page links by Quickdocs's.
updated README.

- added Clack.Middleware.Postmodern to the Middleware section.
- replaced contributor lists by a URL to a GitHub contributor page.
Content-type header is now case insensitive
Merge pull request #59 from PuercoPop/master

Content-type header insentive to case
Extract JSON processing to a middleware

  - Apply it by default in order to mantain compatiblity, not sure it is
  the correct decision.
Complying with the requests of Clack Author.

  json preprocessor as part of the core of clack, hence deleting the .asd
Merge branch 'PuercoPop-master'
Clack.Request doesn't require yason:parse anymore.
Allow basic authenticator to return an user

This will allow the authenticator to also return the object it wants as
remote-user. This is useful when checking the user against a database: it's
possible to transport it to the following middlewares/applications without
having to fetch it again.