Merge pull request bitcoin#380 from achow101/master

Update BIP 144 'havewitness' to service bit

Author: luke-jr

bip-0144.mediawiki

@@ -86,9 +86,10 @@ Currently, the only witness objects type supported are script witnesses which co
 * '''Rationale for the 0x01 flag byte in between''': this will allow us to easily add more extra non-committed data to transactions (like txouts being spent, ...). It can be interpreted as a bitvector.
 
 === Handshake ===
-A new message 'havewitness' is sent after receiving 'verack' to
-indicate that a node can provide witness if requested (similar to
-'sendheaders') (Note: it might be better to signal this with a services bit in the version message)
+A node will signal that it can provide witnesses using the following service bit
+
+    NODE_WITNESS = (1 << 3)
+	
 
 === Hashes ===
 Transaction hashes used in the transaction merkle tree and txin outpoints are always computed using the old non-witness