Update header sharing script

[wrightmartin]

We changed the header design on the home app, and probably broke the header sharing script.

We now have

_header.html.erb (the header, uses all below)
_login.html.erb (a login link and menu, if the app needs it, if not, it's a blank file)
_menu.html.erb (the primary navigation on the 'left' or 'top' (comes first))
_menu_secondary.html.erb (the right hand navigation menu (comes last))

Each app will probably have a completely different primary navigation, and the same secondary navigation (but linking to different places, depending on the context - eg 'github' goes to the relevant repo)

[wrightmartin]

Also there's missing services from the header right now, probably because the script broke, eg the home page has 'science' and 'dashboards' but it's not in all the headers