I was only ever comparing the lowercase version of the name, so this
should be done in a single place (the GenericTag) to make maintenance
easier.
Signed-off-by: Anna Schumaker <Anna@OcarinaProject.net>
Also make it inherit from the GenericTag base class. Also also, add a
unit test specific to Album tags. Finally, I remove the corresponding
section of the DESIGN file since it is no longer needed.
Signed-off-by: Anna Schumaker <Anna@OcarinaProject.net>