Overloaded RequestParams.put() method for adding integer param

Hi,

There is no put() method for adding integer param without casting it to string before passing as an argument to `put(String arg0, String arg1)`

It would be much easier to pass straight integer value.

Before:
`put("ParamName", String.valueOf(1234));`

After:
`put("ParamName", 1234);`

Patch attached.