[SERVDEV-22] / [SERVDEV-26] / [SPARKL-30]

- Added caching ability to cpk kettle endpoints.
- Filtered output steps from which it is allowed to get results when executing a cpk kettle endpoint. Only steps which name begins with "OUTPUT" are eligible.
- Corrected bug which prevented getting a file from the result of a cpk kettle endpoint execution.

Note: Although caching (memory/disk) is functional, I still want to improve it (e.g. allow cache configuration from file). Thus, this merge will not close issue SERVDEV-22.