Sends the response back to the client. Commits the status, headers and
optional entity and send them over the network. The default
implementation only writes the response entity on the reponse stream or
channel. Subclasses will probably also copy the response headers and
status.
Parameters: response - The high-level response.
Effectively writes the response body. The entity to write is guaranteed
to be non null. Attempts to write the entity on the response channel or
response stream by default.
Parameters: entity - The representation to write as entity of the body. throws: IOException -