Saving a line by giving a hash's default value

If you're using a hash for a specific purpose, you can often save
yourself a little trouble by calling Hash.new(default_value) to define
it in the first place, then you don't have to use #||= to initialize new
members.
Extracting default value in score calculator

...Minor code-cleanup, but it makes the intent a bit clearer if the
default score is called as much rather than using 0. (Plus it gives us
the ability to more easily change it later, if needed.)
calls instance var instead of self.var

an attr_accessor (of any flavor) is used by the class itself with an
instance variable of the same name.
Exctracting thumbnail sizes to a constant

...With a comment or two about the placement of things, which is still
sub-optimal.
Removed superfulous returns

Ruby style guides suggest not using explicit returns when an implicit
return will do.
Rearranging importer methods

Using a single level of abstraction in the main method, and moving the
other methods around to be in the same order as they are used.
Renaming variable

Yes, it's in a small scope, but it was large enough that it was
difficult to read and difficult to replace. Worth changing.
Changing logic of comment

Minor change, but the logic of the comment ("if it's not a family,
ignore it, otherwise do something") was the opposite of the code (if
this.is_family? { do_something } else { ignore_it }), so I changed the
comment to match.
Removing a tiny bit of duplication

...Tried to clean it up entirely, but we're using the hashes there in a
weird way (and I commented on that), and specs failed.
Moved class method to top of file

...Also removed self:: from their invocation.
DRY method

Just extracting a small method where logic was duplicated