Swap out Carrois Gothic for Open Sans

Carrois Gothic won't work for us due to its limited character set
and lack of variants in other weights.

Let's give Open Sans a try (it ticks both of the boxes above) and
see how it feels.
Merge remote-tracking branch 'upstream/new-design' into new-design
Merge pull request #54 from ialja/new-design

bringing back the archive learn pages with a warning and link to new site
Merge remote-tracking branch 'upstream/new-design' into new-design
nav order matches events site
google plus page link added to footer
full mailchimp submit form added to index
new og image
Resource countries, pages and layout added