Update fee providing for bitcoin cash, zcash, and litecoin

[cpacia]

Remove the dependency on cpacia/BitcoinCash-Wallet by moving the packages that were used into this repo.

Also switches zcash and litecoin to use the exchange rate based fee provider.

And lowers the default fees to .1 cents, 1 cent, and 5 cents.

[placer14]

Note that travis is also red.

[coveralls]

Pull Request Test Coverage Report for Build 507

• 32 of 45 (71.11%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.5%) to 54.073%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
zcash/wallet.go	0	1	0.0%
zcash/exchange_rates.go	0	2	0.0%
util/currency.go	0	3	0.0%
util/fees.go	32	39	82.05%
<!--	Total:	32	45	71.11%	-->

Totals
Change from base Build 487:	0.5%
Covered Lines:	2828
Relevant Lines:	5230

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💛 - Coveralls