Extensions to Rubydora digital object and datastream APIs

datastream.rb

ACTIVE = 'A'
INACTIVE = 'I'
DELETED = 'D'

def active?
  dsState == ACTIVE
end

def inactive?
  dsState == INACTIVE
end

def deleted?
  dsState == DELETED
end

digital_object.rb

ACTIVE = 'A'
INACTIVE = 'I'
DELETED = 'D'

def active?
  state == ACTIVE
end

def inactive?
  state == INACTIVE
end

def deleted?
  state == DELETED
end

Looks reasonable.