Use Buffer.from instead of Buffer.alloc (compatibility with older node versions)

Author: ZJONSSON

test/unit/connection/test-auth-switch-clear-insecure.js

@@ -26,7 +26,7 @@ server.on('connection', function(incomingConnection) {
   incomingConnection.on('clientAuthentication', function () {
     this.authSwitchRequest({
       authMethodName : 'mysql_clear_password',
-      authMethodData : Buffer.alloc(0)
+      authMethodData : Buffer.from('')
     });
   });
 

test/unit/connection/test-auth-switch-clear-secure.js

@@ -32,7 +32,7 @@ server.on('connection', function(incomingConnection) {
   incomingConnection.on('clientAuthentication', function () {
     this.authSwitchRequest({
       authMethodName : 'mysql_clear_password',
-      authMethodData : Buffer.alloc(0)
+      authMethodData : Buffer.from('')
     });
   });