Add model to translate the RegistrationPeriod, and helper to show the form for setting this value
Remove extra Registration word from RegistrationPeriod#list
add translations for the registration periods static text
translate the eventConfiguration short_name, long_name, location, dates_description
fix view tests for translated items
translate the remaining registrant#contact fields
add ability to translate category#name event_choice#label and event_choice#tooltip
translate the registrant#items page
translate registrant#show page
translate the payment pages
translate registrants#all
update todo