Message: setBodyContent can leave Content-type inconsistant

[predic8]

A call to:

message.setBodyContent(output.toByteArray());

can leave Content-type and Content-Encoding inconsistant.
Maybe we can change the signature to:

message.setBodyContent(output.toByteArray(), String contentType);

to forse the setting of Content-Types. May be provide both methods and migrate to the second.