Modifying contributors in package.json by @brettlangdon request

package.json

@@ -6,7 +6,8 @@
   , "keywords": ["kestrel", "client", "messaging", "queue"]
   , "author": "brett_langdon <brett@blangdon.com> (http://brett.is)"
   , "contributors": [
-      { "name": "brett_langdon", "email": "brett@blangdon.com" }
+      { "name": "brett_langdon", "email": "brett@blangdon.com" },
+			{ "name": "pablo_casado", "email": "p.casado.arias@gmail.com" }
     ]
   , "repository":{
         "type": "git"