Fix exception message formatting

If the exception class made a reference to the "message" field in
its format string, it would be overriden with the value of the
"message" argument itself. It is now possible to use the "message"
field and preserve the desired message formatting. Test cases
provided.

Change-Id: I5705203466535fa242d13e43571012e5bf72712a
Closes-Bug: #1288066
Merge "Fix exception message formatting"