Cleanup and refactor - version 3.0.0

[coder5876]

This is a big release with the following highlights:

• Major cleanup - you'll most likely need to update your code if you use lightwallet.

• Remove legacy constructor - now only createVault is supported. Also createVault now require seed and hd path as inputs.

• Remove deriveKeyFromPassword function in favor of keyFromPassword function.

• Remove special handling of encryption keys in the keystore. You can still use keystore keys to encrypt, but they no longer use pubkeys to index. To get the pubkey corresponding to an address, please use the function encryption.addressToPublicEncKey.

• Make the keystore and interfaces simpler by only allowing one hdPathString. If you need to derive from more HD paths you need to create more keystores.

• Add 0x prefix for all addresses and transaction hex data.

• Remove unneeded bitcore-lib package dependency. Thanks to Srirangan.

[coder5876]

Since this is a big update I'd like some eyes on it before I merge it in. Hopefully in a week or two it should be good to go.

[coder5876]

Thanks @dekuyper for the review! I’ll make updates with your suggestions and try to merge this in soon!