New Batcher!

DESCRIPTION:
- Added a new way to compute a batch of crc32c. 3x perf improvements with 100 reps and more.
- Updated the README.md with the new way to compute
- Added some examples in test.js of how to use the Batcher.
- Renamed crc32c.cpp to crc32c.cc
- Added the new files in the binding file
- Bumbed to 0.3.0

Signed-off-by: dozoisch <hugo@dozoisch.com>