Closes #3178 by adding verbosity level improvements to getblock RPC.

This is a follow-up commit for d0a1d833520d120bb5a2ac4cf4192047af6afe24
found in PR #3095 in order to fix nits and add a test.

qa/rpc-tests/merkle_blocks.py

@@ -7,6 +7,7 @@
 # Test merkleblock fetch/validation
 #
 
+import string
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.authproxy import JSONRPCException
 from test_framework.util import assert_equal, assert_raises, \
@@ -86,5 +87,13 @@ class MerkleBlockTest(BitcoinTestFramework):
         # ...or if we have a -txindex
         assert_equal(self.nodes[2].verifytxoutproof(self.nodes[3].gettxoutproof([txid_spent])), [txid_spent])
 
+        # Quick test of getblock using blockhash and different levels of verbosity
+        result = self.nodes[0].getblock(blockhash, 2)
+        coinbase_txid = result["tx"][0]["txid"]
+        result = self.nodes[0].getblock(blockhash, 1)
+        assert_equal(coinbase_txid, result["tx"][0])  # verbosity 1 only lists txids
+        result = self.nodes[0].getblock(blockhash, 0)
+        assert(c in string.hexdigits for c in result) # verbosity 0 returns raw hex
+
 if __name__ == '__main__':
     MerkleBlockTest().main()