add feedback link and basic HTTP auth; darken table borders

close #41, close #43
hide contributor names and language comments

for the purposes of the presentation
improve map icons; add WALS link
Merge branch 'master' into prelaunch
change colors on Arguments table in Verbs#show
Merge branch 'map' into prelaunch
Merge branch 'master' into prelaunch
remove basic HTTP auth
update README
Merge branch 'master' into prelaunch