Enable log messages to handle exceptions containing unicode

Currently the format string is a normal string, which in
py2x is not unicode.  When the unicode exception information is
used to replace the %s, str() is called on it, but because
it is unicode str() fails.  Making the format string unicode
fixes this.  For the error log this is done by making it
translatable and for the debug message by explicity making
it unicode.

The exception will contain unicode when the exception being
returned by the other project is either translated to a
language using unicode characters or when lazy translation
is enabled and a gettextutils.Message instance is returned.

Change-Id: I1706f5eb9dfbee434f8882b03dad4674d955c370
Closes-Bug: #1310397
Merge "Enable log messages to handle exceptions containing unicode"