Closes #1097 so zcash-cli now displays license info like zcashd.

LicenseInfo is refactored from init.cpp to util.cpp so that the
bitcoin-cli makefile target does not need to be modified.

src/init.h

@@ -34,7 +34,5 @@ enum HelpMessageMode {
 
 /** Help for options shared between UI and daemon (for -help) */
 std::string HelpMessage(HelpMessageMode mode);
-/** Returns licensing information (for -version) */
-std::string LicenseInfo();
 
 #endif // BITCOIN_INIT_H