Issues with using tna-base with blog

[grange85]

Now that we are using tna-base with blog it is introducing issues that mean we are having to put hacks in place because of the differences in infrastructure and urls - the three examples I'm aware of:

• The path to the megamenu is different so has been hacked in the tna-base on blog
• The URLs in the headers have a replace that puts www in the url (this on the website is to change livelb to www - but it's also changing blog to www - which is breaking the yoast generated urls (open graph and caonical) - fixed with a hack in tna-base on blog
• When a page is not found on blog the 404 page is converting it to a www link e.g. http://www.nationalarchives.gov.uk/blog/bridging-digital-gaps/ (not fixed)

All of this means that maintaining and updating tna-base on blog is tricky and prone to errors that will break the site because we need to ensure that the hacks aren't over-written

[grange85]

Not necessary to fix as it will be accommodated by wider blog updates