Fix Errors#from_type use known_attributes

This commit replaces the use of #attributes.keys with #known_attributes
in Errors#from_array and Errors#from_hash. This is done so that when
ActiveResource grabs errors for attributes defined in the schema, but
don't yet exist as an attribute on the object, the error gets assigned
to the known attribute instead of the base object.
Merge branch 'master' into fix/errors-from_type/use-known-attributes

* master:
  Updating changelog.
  Adding `lib/activeresource.rb` to the project.
Merge pull request #118 from DisruptionCorporation/changelog

Changelog :-)
Merge pull request #100 from DisruptionCorporation/has-one-for-non-singleton

has_one fallback works when target is not a Singleton
Merge pull request #90 from MorganShowman/fix/errors-from_type/use-known-attributes

Fix Errors#from_type use known_attributes
Quick fix for JSON root setting in CustomMethods

This is probably not a proper and complete fix, but the gist is that
support for the include_root_in_json settings are handled in Base when
they ought to be considered in the Format classes as well.
CustomMethods knows nothing about the config handling done in Base so
it's stuck with the unconfigurable default before this change.
Merge branch 'custommethods-root-quickfix' into integration

* custommethods-root-quickfix:
  Quick fix for JSON root setting in CustomMethods