Upgrade to Rails 4.1.4

This is a first pass at upgrading the app to Rails 4.1.4.

Being new to the codebase, I am not sure about what areas might be "gotchas" that the test suite doesn't cover, or that might be worth running through manually in the web browser.  If you want to point me in that direction, I am happy to do the legwork.
It works because Rails doesn't try to infer anything about the conditions you're passing into `where`; it will just evaluate that SQL.

This will also work, and I think it's closer to the spirit of the original code you wrote:
```ruby
 has_many :admins, -> { where(membership: { admin: true }).order(:last_name, :first_name) }, through: :memberships, source: :person
```

That's probably the "right way" to do it.