Add RPC methods for exporting/importing viewing keys

src/rpcclient.cpp

@@ -114,6 +114,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "z_getoperationstatus", 0},
     { "z_getoperationresult", 0},
     { "z_importkey", 2 },
+    { "z_importviewingkey", 2 },
     { "z_getpaymentdisclosure", 1},
     { "z_getpaymentdisclosure", 2}
 };