Let invites be declined.

app/controllers/invites_controller.rb

app/mailers/emails/groups.rb

app/mailers/emails/projects.rb

app/models/member.rb

app/models/members/group_member.rb

app/models/members/project_member.rb

app/services/notification_service.rb

app/views/invites/show.html.haml

app/views/notify/group_invite_declined_email.html.haml

app/views/notify/group_invite_declined_email.text.erb

app/views/notify/group_member_invited_email.html.haml

app/views/notify/group_member_invited_email.text.erb

app/views/notify/project_invite_accepted_email.text.erb

app/views/notify/project_invite_declined_email.html.haml

app/views/notify/project_invite_declined_email.text.erb

app/views/notify/project_member_invited_email.html.haml

app/views/notify/project_member_invited_email.text.erb

config/routes.rb

spec/models/members_spec.rb