added a subdir for results/data retrieved from each CASU

[rmm-fcul]

• resolves #59
• tested with a simple setup that has a non-unique filename for a log created by the casus ("calibration.log"), with >1 casu in a single layer. Older version clobbers the earlier downloads while the new version preserves correctly.

oldver/ └── data_demo └── sim-arena1 ├── 2016-06-03-17-24-51-casu-sim-008.csv ├── 2016-06-03-17-24-51-casu-sim-009.csv └── calibration.log

newver/ └── data_demo └── sim-arena1 ├── casu-sim-008 │   ├── 2016-06-03-17-24-51-casu-sim-008.csv │   └── calibration.log └── casu-sim-009 ├── 2016-06-03-17-24-51-casu-sim-009.csv └── calibration.log