System settings page fixes

1. System.html Don't submit when nothing has changed.
2. sync the file system after writing system settings.

octoserve/var/www/system.html

@@ -106,7 +106,11 @@ function SaveSettings()
       param += "strict=" + (NewSettings.strictEnabled?"1":"0");
     }
     
-    location.replace('/systemsettings.lua?'+param);
+    document.getElementById("SetButton").disabled = true;
+    if( param != "" )
+    {    
+      location.replace('/systemsettings.lua?'+param);
+    }
   }
 }
 

octoserve/var/www/systemsettings.lua

@@ -165,6 +165,7 @@ if query ~= "" then
         if name == "strict" then restart = 1 end
       end
     end
+    os.execute("/bin/sync >/dev/null 2>&1");
     if restart == 1 then 
       os.execute("/etc/init.d/S99octo restartoctonet > /dev/null 2>&1 &")
       nextloc = "wait.html?10"