Implement remaining endpoints api/transactions/single and api/broadcast/*

[stdevAlDen]

• Implement endpoints of type api/transactions/
• Implement endpoints of type api/broadcast/

[stdevAlDen]

I am implementing tests for real transactions in Likke. The idea is checking balance for a given address before and after confirming a transaction, so that balance after transaction is equal to the balance before plus the amount transfer. But what about is the blockchain is updated in the mean time and the final balance is not the expected one? This is perfectly possible because tests are made starting from a blockchain downloaded from https://transfer.sh, which is always the same, it is not updated after every test. So, this blockchain may be outdated a few transactions from the real blockchain.