changing how ban system works

instead of using radio buttons limiting a user being able to ban a person from one board at a time this commit changes that so it uses checkboxes instead along with this commit the file located in /templates/mod/ban_form.html will also have to be modified so that the type for the dom node named "boards" has the type "checkbox" instead of what it is now, along with this change the name value should be changed from 'boards' too 'boards[]'.

It still works the same filing each ban individually.