[Opensource] missing message in bundle: error msg, not exception

[larry hamel]

in MessageBundle.java,
    public String getString(String stringCode, Object[] args)

used to throw IllegalArgumentException if a translation was not found.  this breaks the entire call for lack of a single string, potentially.

it seems better to log an error message and return the supplied key in the case where a string for the key cannot be found, rather than throwing an exception.

I've changed the code to this effect.

larry