Change island.is header to send the user to island.is

Instead of linking to the home page this should link to the
"mothership" (which is island.is).
Make font size smaller for inputs with prepended add-ons

Input fields with prepended add-ons (wrapped in a div with the
class input-prepend) are smaller than the usual fields so we need
to set the font size on the wrapping div to inherit the font-size,
making it smaller and thereby fixing the bug where users can't see
what they're filling in.
Add Þjóðskrá Íslands footer

Island.is pages have a standard looking footer which needs to be
on the CKAN instance as well. Slightly modified from the island.is
look to incorporate information about CKAN and the CKAN API (and
also because the CKAN content width is less than the other island.is
pages).