v2.3 BCM Banner Implementation

• removed emediate code from Banner Class
• added loads of new bcm fields
• refactored some of the admin to accommodate for new bcm fields
• removed the "manual" switch for enabling the banner script on sites that doesn't have WA shell
• added the option to display WA middle banners, if there's a shell and "show banners" is disabled in wa-externa-shell-v2
• moved all constants into the files, of which it is used
• refactored the required bcm meta tags, into a function, so that we do not run multiple lines that do the same
• refactored getOptionOrDefault() function