fix indentation for join statement in blood_type class.
rename method for join statement in blood_type class.
make 'list_locations_for_type' method so that user can be able to see all donation locations that hold a blood type.
fix main menu in UI.
update 'list_types' method in UI so that user input the ID of a Blood Type and have participating donation locations returned.
refactor UI by adding a search method to delete 'list_types' method and 'list_locations' method.
add 'assign' method to UI so user can assign blood types to a donation location. /WIP/.