[Issue #162] Adding missing space to stringByAddingPercentEncodingWithAllowedCharacters character set

Source/Alamofire.swift

@@ -151,7 +151,7 @@ public enum ParameterEncoding {
     }
 
     func escape(string: String) -> String {
-        let allowedCharacters =  NSCharacterSet(charactersInString:"=\"#%/<>?@\\^`{}[]|&").invertedSet
+        let allowedCharacters =  NSCharacterSet(charactersInString:" =\"#%/<>?@\\^`{}[]|&").invertedSet
         return string.stringByAddingPercentEncodingWithAllowedCharacters(allowedCharacters) ?? string
     }
 }