Add participants
Update signup form
do not style all inputs
fix submit button styling
rearrange checkboxes
add some space to checkboxes
Leave only really required fields for signup
Cleanup _signup partial
Add simple_form
Add validations on client
Add flash messages
Add styles for flash messages
Add pry
Add uniqueness check for email. Set default locale to :ru
I18n for signup
:en translations for signup
Add letter_opener
Add mail_safe
Send email after signup
Apply review comments

Use single quotes
Move link to form from templates to mailer
Remove empty line