Remove useless bitcore-lib dependency [don't merge]

[dakk]

At the moment btcnodejs uses bitcore-lib only for HD path derivation while bitcoinjs-lib is used for many other things; I propose to remove bitcore-lib dependency, by using the bitcoinjs.HDNode class instead for HD path derivation purpose.

Todo:

• _setParams
• improve the test suite by importing tests from btcpy (https://github.com/chainside/btcpy/blob/master/tests/unit.py#L135)

[dakk]

These are the fields set by _setParams, with their corresponding field (if present) of bitcoinjs.HD:

• depth : Integer (present, same name)
• fingerPrint : Integer (not present, but getFingerprint())
• parentFingerPrint : Integer (present, but named parentFingerprint)
• childIndex : Integer (present, but named index)
• chainCode : String (present, same name)
• checksum : Integer (not present)
• xpubkey : String (not present, but toBase58())
• xprivkey : String (not present, but toBase58())
• pubkey : Publickey object (set by constructor using crypto)
• privkey : Privatekey object (set by constructor using crypto)

I will implement _setParams maintaining the old field names. Can you please provide me a test case for verifying these values?

[d0ze]

Sorry for taking so long for answering to that PR. I will implement the _setParams and merge the pull request all togheter. I will just fix the initialization of both HDPublicKey and HDPrivateKey object when no params are provided in the constructor to throw an error since a null internal key should not be allowed.
Thank you for the contribution!

[dakk]

Thank you too for reviewing it, pleased to being helpful