Replace the "buffer-crc32" with "jhash". jhash will create shorter sum result
and the performance is better.

Here's a simple benchmark's source code:
https://github.com/ysmood/nobone/blob/5e36ea738a57c69dce839eb2e595a4be2a73737d/benchmark/crc_vs_jhash.coffee
Update the test cases with the jhash.