Denormalize Album class and embed it to Track entity

[AddictedCS]

Album model can be safely embedded into Track as it represents mainly read only information (it will be updated only in case if an error is introduced, which is unlikely). Having a typical read only model, would suggest denormalizing it into Track:

• Album name
• Album release year (is it really useful?)

Mark those fields as nullable (in case when album information is not known).

[AddictedCS]

Done.