Add activerecord-51 gemfile

[ALacker]

Allow activemodel-associations to work with rails 5.1.1, specifically the new add_constraints:

https://github.com/rails/rails/blob/5d9d6a4fbf72029266bfa643929a9a80f9286fbe/activerecord/lib/active_record/associations/association_scope.rb#L123

Solves #13

[coveralls]

Coverage decreased (-1.8%) to 91.346% when pulling 264115a on ALacker:update-51 into 8bbea47 on joker1007:master.

[coveralls]

Coverage decreased (-5.6%) to 87.5% when pulling c07095c on ALacker:update-51 into 8bbea47 on joker1007:master.

[joker1007]

Thanks!!
But almost spec is failed.
Would you fix migration error and AR-51 spec failure?

[ALacker]

On it, annoyingly the tests are now working when running individually, but failing (sometimes) in group. I first blamed http://edgeguides.rubyonrails.org/5_1_release_notes.html#transactional-tests-with-multiple-connections but disabling transactional tests doesn't help

[coveralls]

Coverage increased (+1.3%) to 94.393% when pulling 8dab104 on ALacker:update-51 into 8bbea47 on joker1007:master.

[jeznag]

Any updates @ALacker ?

[TrishaPatel]

I am getting an wrong number of arguments error in activemodel-association.
Can anyone help me?

[CodingAnarchy]

It looks like this was never merged and ActiveRecord changed again for Rails 5.2, which breaks even this attempted fix.