Don't modify nil getnetworkinfo result.

Since the result might not be set when the response does not contain one,
such as in the case when the command is not implemented by the server,
don't attempt to modify it until ensuring it exists.
Update ListReceivedByAddressResult txids field.

The name of the field in the returned JSON is txids, not tx.
update ValidateAddressResult for IsWatchOnly
Merge pull request #1 from mably/confmerge

ppc: merged conformal/master, tests ok
Merge remote-tracking branch 'remotes/origin/master' into mably