add observations to to_h

lib/avm/image.rb

@@ -322,6 +322,7 @@ module AVM
     def to_h
       hash = Hash[HASH_FIELDS.collect { |key| [ key, send(key) ] }]
       hash[:creator] = creator.to_a
+      hash[:observations] = observations.collect(&:to_h)
       hash
     end
 

spec/avm/image_spec.rb

@@ -172,7 +172,8 @@ describe AVM::Image do
       :metadata_date => Time.parse(metadata_date),
       :metadata_version => metadata_version,
       :subject_names => subject_names,
-      :categories => categories
+      :categories => categories,
+      :observations => []
     } }
 
     its(:distance) { should == [ light_years, redshift ] }