Replace the "buffer-crc32" with "jhash"

jhash will create shorter sum result and the performance is better.
It don't have to waste cpu to encoding a string into a buffer before calculating the hash.

Here's a simple benchmark's source code:
https://github.com/ysmood/nobone/blob/5e36ea738a57c69dce839eb2e595a4be2a73737d/benchmark/crc_vs_jhash.coffee

Here's the project home:
https://github.com/ysmood/jhash

As we can see, jhash is about 1.5x faster than crc32.
Their results of collision test are nearly the same.
```
Performance Test
crc buffer   x 5,903 ops/sec ±0.52% (100 runs sampled)
crc str      x 54,045 ops/sec ±6.67% (83 runs sampled)
jhash buffer x 9,756 ops/sec ±0.67% (101 runs sampled)
jhash str    x 72,056 ops/sec ±0.36% (94 runs sampled)
Collision Test
***** jhash *****
 5 samples: 3481292839,1601668515,957061576,1031084327,1000054056
      time: 10.001s
collisions: 0.0018788163457017504% (4/212900)
***** crc32 *****
 5 samples: 3494480258,2736329845,2815219153,3510180228,2016919691
      time: 10.003s
collisions: 0.0027945971122544933% (6/214700)
You cannot remove `encoding`; it is not there for no reason.