Fix 2 small issues in sporks module (#2133)
Fix 2 small issues in sporks module (#2133)

* Fix a crash when someone tries to update sporks without specifying `sporkkey`

Before:
Crashes with `Assertion failed: (fValid), function GetPubKey, file key.cpp, line 156.`

After:
Fails and prints rpc help for `spork`

* Silence logging in CSporkMessage::CheckSignature() a bit

CMessageSigner::VerifyMessage() failure is not really an error
if CHashSigner::VerifyHash() below passes with no issues.
No need to log this.

biblepay/biblepay,dashpay/dash,thelazier/dash,nmarley/dash,ionomy/ion,nmarley/dash,nmarley/dash,crowning-/dash,UdjinM6/dash,thelazier/dash,crowning-/dash,biblepay/biblepay,biblepay/biblepay,thelazier/dash,biblepay/biblepay,ionomy/ion,biblepay/biblepay,ionomy/ion,ionomy/ion,UdjinM6/dash,dashpay/dash,dashpay/dash,crowning-/dash,UdjinM6/dash,ionomy/ion,UdjinM6/dash,ivansib/sibcoin,ivansib/sibcoin,nmarley/dash,ivansib/sibcoin,crowning-/dash,biblepay/biblepay,UdjinM6/dash,thelazier/dash,biblepay/biblepay,dashpay/dash,biblepay/biblepay,thelazier/dash,ivansib/sibcoin,nmarley/dash,crowning-/dash,nmarley/dash,ivansib/sibcoin,nmarley/dash,ivansib/sibcoin,dashpay/dash,ionomy/ion,crowning-/dash