fix some ortography
add omniauth-google-oauth2 gem to Gemfile
rewrite find_or_create_for_google_oauth2 method
add google_oauth2 as omniauth provider
remove routes for deprecated crowdint_auth
refactor users table migration
rename migration that adds omniauth columns to users
add migration for columns with personal data to users
run pending migrations
add Hubot image
add styles for home page
add omniauth callback for google_auth2
update login feature spec