Refactored SinkMode
- Added SinkMode To TestTapFactory.
- SinkMode is no longer conditionally set depending on access mode.
Add scalding logo

Added Scalding logo to the README and also linked to the full artifacts:
https://drive.google.com/folderview?id=0B3i3pDi3yVgNbm9pMUdDcHFKVEk&usp=sharing

Signed-off-by: Chris Aniszczyk <zx@twitter.com>
Merge pull request #671 from twitter/add-logo

Add Scalding logo
Update README.md
Update README.md
Update README.md
Update README.md

Fix small issue in README
Merge pull request #662 from pcting/fix/sinkmode

SinkMode Clean Up