Fixed stack overflow for editing deceased person

Two errors in Errbit showed a stack overflow on contact#update and both had deceased=true in the parameters. It turns out that `person.deceased_check` can cause infinite recursion when you edit a deceased contact because the `Contact.greeting` method doesn't just return a field, but rather defaults to contain the first name of the contact (which deceased_check is trying to remove). My fix is to directly access the field via [] and not call the Contact.greeting method.

I also added a cmd: argument to the `Guardfile` for rspec becaues `guard` started to complain to me about not having it. Not sure why that complaint started now. Guard also updated the Gemfile.lock for github based gems automatically.