rpc: Add admin_addTrustedPeer and admin_removeTrustedPeer.

These RPC calls are analogous to Parity's parity_addReservedPeer and
parity_removeReservedPeer.

They are useful for adjusting the trusted peer set during runtime,
without requiring restarting the server.

internal/web3ext/web3ext.go

@@ -123,6 +123,16 @@ web3._extend({
 			call: 'admin_removePeer',
 			params: 1
 		}),
+		new web3._extend.Method({
+			name: 'addTrustedPeer',
+			call: 'admin_addTrustedPeer',
+			params: 1
+		}),
+		new web3._extend.Method({
+			name: 'removeTrustedPeer',
+			call: 'admin_removeTrustedPeer',
+			params: 1
+		}),
 		new web3._extend.Method({
 			name: 'exportChain',
 			call: 'admin_exportChain',