Improved comments on Stream::handle().
Don't use void returns.
Unused usages.
Fixed docblock for WorkerHandler::getStream().
Fix timeout issues between Client and ClientHandler.

The function handle may not take longer than MAX_MANAGER_DELAY, otherwise the Client will
get a "AlphaRPC did not respond in time" message.
Fixed execution time of WorkerHandler::handle().

This prevents a timeout between ClientHandler and WorkerHander.
When the timeout occurs, the ClientHandler will invalidate the WorkerHandler
which results in a redispatch of all jobs.
Send a heartbeat every WorkerHandler::handle() call.

This is to prevent the WorkerHandler from being invalidated in
the ClientHandler.
Merge pull request #27 from alphacomm/bugfix-timeouts

Fixes a few potential time-outs in the ClientHandler and WorkerHandler.