Height should be UInt64

[dgarcia360]

height in BlockInfo is returned as a UInt64 string but some functions demand this parameter as a string:

BlockHttp

• getBlockTransactions
• getBlocksByHeightWithLimit
• getMerkleTransaction
• getBlockByHeight

ReceiptHttp

• getBlockReceipts
• getMerkleReceipts

Ideally, the above-mentioned functions should accept height as a UInt64 to be more consistent.