Valkyrie::ID#eql? and == should return true when a string is compared with an equivalent Valkyrie::ID

[hackartisan]

We would like all 3 examples to return true. === should continue to return false.

[11] pry(main)> id = Valkyrie::ID.new('abc')
=> #<Valkyrie::ID:0x007fdee25d4760 @id="abc">
[12] pry(main)> id.eql?('abc')
=> false
[13] pry(main)> id == 'abc'
=> false
[14] pry(main)> id == Valkyrie::ID.new('abc')
=> true

[tpendragon]

I didn't do this on purpose for some reason and now I don't remember why, so okay.

[no-reply]

Related to #765

[no-reply]

Happy to implement this, if there's broad agreement it's desirable.

It's probably a major version, once in.