Add the with-additional-middleware macro

`with-additional-middleware` concats the given middleware sequence to
the beginning of *current-middleware* for the given body

Resolves dakrone#227

Author: dakrone

changelog.org

@@ -68,6 +68,8 @@ List of user-visible changes that have gone into each release
   and clean up whitespace for new clojure-mode
 - Merged https://github.com/dakrone/clj-http/pull/171 to support SOCKS proxies
 * Work log
+** 2015-02-08
+- Add the `with-additional-middleware` macro
 ** 2015-01-19
 - merged https://github.com/dakrone/clj-http/pull/248 to removed deprecated
   cookie APIs from cookie.clj

src/clj_http/client.clj

@@ -896,6 +896,15 @@
                                                m#)]
        ~@body)))
 
+(defmacro with-additional-middleware
+  "Perform the body of the macro with a list of additional middleware.
+
+  The given `middleware-seq' is concatenated to the beginning of the
+  `*current-middleware*' sequence."
+  [middleware-seq & body]
+  `(with-middleware (concat ~middleware-seq *current-middleware*)
+     ~@body))
+
 (defmacro with-connection-pool
   "Macro to execute the body using a connection manager. Creates a
   PoolingClientConnectionManager to use for all requests within the body of