Added missing colon in asset manifest JSON.
Merge pull request #15860 from aidanharan/docrails-assets-manifest-typo

[ci skip] Added missing colon in asset manifest JSON
Remove old deprecation warning

This has been around for a couple of versions now, a `NoMethodError`
should suffice at this point.
`reload` should fully reload attributes

`reload` is meant to put a record in the same state it would be if you
were to do `Post.find(post.id)`. This means we should fully replace the
attributes hash.
Add missing test cases for `attribute_names` instance method

There is a class method with the same name that is tested, but not the
instance method.
Merge pull request #15866 from sgrif/sg-reload-attributes

`reload` should fully reload attributes
Merge pull request #15865 from sgrif/sg-missing-test

Add missing test cases for `attribute_names` instance method
Merge pull request #15848 from sgrif/sg-remove-deprecation

Remove old deprecation warning
changelog entries for #15866 and #15848

/cc @sgrif