Proposal to fix for #1753

Proposal to fix for #1753

Create constructors for Multipart CODEC with extra argument unlimitedMethod to allow to bypass test of method used.

By default (false), only PUT, POST, PATCH and OPTIONS are allowed.
If true, all methods are allowed.

This fix tends to allow body in request as it seems allowed in RFC 2616 (or not forbidden), but not implemented.
This will allow Netty to support this if needed, for instance for REST implementation where GET could use a Body as request part.

Note also that both Encoder and Decoder now support by default the same subset of methods:
- POST, PUT, PATCH and OPTIONS
While before:
- Encoder was supporting only POST
- Decoder was supporting only POST, PUT and PATCH