Support compressed public keys in PrivateKey.js
save private keys in base58 format

...to allow them to be imported into other wallets, preserving the "compressed"
or "uncompressed" state of the public key in the private key representation.
fix validate math error
Merge pull request #9 from ryanxcharles/feature/compressed-public-keys

Save private keys in base58check encoded format
Merge remote-tracking branch 'upstream/master' into task/readme
various small changes to bitcore