Use base_class rather than superclass

[bufordtaylor]

I've had some issues with this gem after updating to rails 5.

Upon installation, the object.follow(thing) works fine the first time, but every time thereafter, it fails with:

TypeError: no implicit conversion of nil into String

It's because ApplicationRecord is the class that parent_class_name is returning. You can see by this query:

INSERT INTO "follows" ("followable_id", "followable_type", "follower_id", "follower_type", "created_at", "updated_at") VALUES (14829, 'ApplicationRecord', 1, 'User', '2017-01-15 09:49:16.098371', '2017-01-15 09:49:16.098371') RETURNING "id"

I've done all the recommended steps with the config and I was about to give up until I saw that you're using superclass, which doesn't always provide the right class in a rails environment:

class A < ActiveRecord::Base
end

class B < A
end

> A.superclass
=> ActiveRecord::Base
> B.superclass
=> A

> A.base_class
=> A
> B.base_class
=> A

I added this commit to my own forked branch and it now works as expected: bufordtaylor@43ad8ae

[jeremylynch]

This is a duplicate of #56

[brchristian]

@bufordtaylor Now that #56 has been merged, are you still experiencing this issue?