Changing product space node size scale

When size encodes world trade
Added and styled submit button for product and country forms.
Working on making the Go button work, still buggy.
Added the Standard Bank Group to supporters.
Fixed typo.
Leftover work on go btns that I forgot to save.
Get phantomjs temp dir from settings.
Submit buttons for country and product dropdowns now works.
Merge branch 'beta' of https://github.com/cid-harvard/atlas-economic-complexity into beta
Merge pull request #327 from cid-harvard/beta

Added Standard Bank to the about page and footer, added submit button to the homepage country and product dropdowns