Fix issue with Google Analytics event tracking

GA event tracking does not support arrays as input. Instead, we send an
stringified version of the array we want to track.
Add contact information in footer

Add email and link to Github Issues in footer
Rename INSTRUCTIONS from .md => .txt
Add social buttons

Add buttons to share on Facebook, Twitter, G+
Fix alignment issues with the gallery view

Displaying the gallery view on larger screens was resulting in alignment
issues. Using rows for each new row fixes the issue.
Fix value for Google Analytics event tracking

The correct string is now being sent to GA whenever someone hits
'Download'