PDI-11948 - Error in sub-transformation If "KETTLE_DEFAULT_SERVLET_ENCODING" in set to UTF-8.

Fixed steps:
1) Mapping
2) Trans Executor
3) Simple Mapping
4) Single Threader
Provided JUnits also covered all steps and setServletReponse method of Trans objects.
Merge pull request #564 from  YuryBY/PDI-11948