uninitialized constant Carddav::AddressBookCollectionResource::ALL_PROPERTIES

[kristianm]

I noticed that the newly added AddessBookCollectionResource added in 8c67d87 didn't define some constants as the other resources do. I added this to my fork

# /app/models/carddav/address_book_collection_resource.rb

  ALL_PROPERTIES =  {}
  EXPLICIT_PROPERTIES = {}

but didn't add this into pull request since I couldn't foresee the consequences.

[inferiorhumanorgans]

If it works for you and passes the specs, I'd be happy to merge it. Travis is currently setup to only test w/ Ruby 1.9.3, but should probably be setup to test w/ 2.0 and 2.1.