Portal - multi-lingual functionality

1. Make all pages translatable via Crowd-In

• We believe that alot of pages are already set up to be translatable via Crowd-In (with the json keys)
• Please survey the portal site to identify the pages that still require this functionality to be added (make a note of the pages you identify)
• Add this functionality
• Meanwhile, @lmstarke to translate the portal pages via Crowd-In (this should highlight the final pages still without translation abilities)

2. Add language switcher UI

• Create the front end language switcher UI
• This is the same as we have on staging.fieldkit.org:
  • Designs:
    • Desktop: https://zpl.io/8lBOPQ6 and https://zpl.io/mDzgyLK 
    • Mobile: https://zpl.io/1yoLdn4