Make P4Ruby include the text of any errors or warnings in exception
messages. Previously the user had to call P4#errors() and/or P4#warnings()
to display this information and if you didn't handle P4Exception specifically
the message could look somewhat cryptic. This change hopefully makes it
easier - particularly for newbies.
Note that the text of warnings is not shown unless you're using
exception level 2 (P4::RAISE_ALL).