update changelog

Author: dakrone

changelog.org

@@ -269,6 +269,7 @@
    - merged https://github.com/dakrone/clj-http/pull/124 to handle
      URL-encoding invalid characters in the URI
    - bump cheshire to 5.1.0
+   - Switch from deprecated SingleClientConnManager to BasicClientConnectionManager
 ** 2013-04-01
    - merged https://github.com/dakrone/clj-http/pull/126 to bump
      httpcore version