Add gear button to allow selection of attributes for web UI table

[vkuznet]

We should provide uniform web UI experience to end-users and since we settle down on using gear icon on main FOXDEN pages I suggest to adapt the similar button (and web UI) to SpecScan table template. Please have a look at dyn_table template how it is down.

Also, we should move all CSS styles from template into css/top.css to avoid overlap in styles which can be difficult to trace and debug (for that please use dedicated and unique style names for your HTML tags).