package: add npm test target
package: sort
tests: switch to for(it( style
bs58: use Buffers for internal calculation

Ported from bitcoinjs-lib, uses BigInteger precomputation as well.
CHANGELOG: adds latest changes
1.1.0
Remove bigi dep, optimize byte operations
Merge pull request #6 from deckar01/pure-js-2

Remove bigi dep, optimize byte operations
readme: added credits
1.2.0
bs58: use push instead of unshift
bs58: avoid comparison, check if property exists