Add Query Support

[YelloooBlue]

When using this library, I have the same problem #37
I tried to make a few small modifications and it worked fine.

Before I added query support, queries were parsed as part of URI_PATH

coap.put(IPAddress(10, 0, 1, 1), 5683,"room/lights?n=bed&s=on","hello");

the Option will be resolved as

Option_URI_PATH : room
Option_URI_PATH : lights?n=bed&s=on

Based on the position of '/','?' and '&' characters, the path and query are separated

Option_URI_PATH : room
Option_URI_PATH : lights
Option_URI_QUERY : n=bed
Option_URI_QUERY : s=on

It supports the following cases:

1. No URI_PATH parameter (root path)
2. No URI_QUERY parameter
3. Only URI_PATH without URI_QUERY.

The original functions are not affected.
Thanks.

[hirotakaster]

@YelloooBlue
Thank you for your PR.
I will test now.