Added dehydrate method to extract emails and expose them to the API
JSON as default format
f/#68 serialize only to json
f/#68 move serializer setting to BaseResource
f/#68 removed determine_format functions from all resources - json format is now assured by the serializer in BaseResource
f/#68 moved contact emails function to model
f/#68 commented the get_contact_emails function
Merge pull request #91 from aismail/f/#68-apify-contact-emails

F/#68 apify contact emails