v0.5.1

• Readable:
  • now, when readable have read_mark_id, it will first verify that the read_mark_id is from the same user passed in the parameters
  • Added read_by scope
• Reader:
  • created have_not_read? instance method, which works with its own with_read_marks scope, verifying as well that the read_mark id belongs to the readable passed in the parameters
  • created with_read_marks, have_read and have_not_read scopes for the user