Add support for different message body encoding than ASCII

[Mihael Schmidt]

The Content-Type HTTP header can contain the charset for the message body. It needs to be mapped to the corresponding CCSID. Then the message body needs to be converted using that CCSID.

Note: The message header needs to be converted from ASCII as it is always in ASCII.

[Mihael Schmidt]

message body will now be encoded on receiving data, resolved issue #24

→ <<cset 884d0a16194e>>