Changing dpath in line with SLIP-044

[Varunram]

Right now, go-musicoin uses 60 as the dpath whereas according to SLIP-44, we ought to use 184. Changing the dpath should not affect most people and shouldn't affect implementations that do hd key derivation correctly, but in the case they fall back to the default one (60 in the case of gmc right now), we are at loggerheads with MEW/MyCrypto. The current situation is that people who create an account on the Musicoin Desktop Wallet and move it to trezor / ledger need to choose 60 on the relevant screens while unlocking the wallet.

One obvious solution is to merge #96 and move forwards with a minor version release. This would require back port fixes in the desktop wallet. The other is to keep 60 as is but call the dpath on the desktop's side, which would mean we need to get rid of the ethers.js package which we use in the wallet right now (since one of the package's routes doesn't support attaching a dpath to it). The third is to get rid of mnemonics on the desktop wallet side and then upgrade the dpath in gmc. Other implementations like trezor and ledger implement hd properly, so they should function as normally.

Open to suggestions.

[immartian]

correlated MyCryptoHQ/MyCrypto#2253