Fixed server hang when BERT.decode fails

[tpett]

When the BERT portion of a BERP fails to decode correctly via BERT.decode in a Ruby handler the exception is not caught. This causes the Ruby handler to exit without notifying the erlang process which continues to wait indefinitely for a response. A few bad requests and all Ruby handlers are down until Ernie is restarted.

This (tested) patch wraps the decode process in a begin...end block rescuing any errors and returning them as expected by the protocol.