Namespaced scopes perform incorrect queries

[kranzky]

Describe the bug
Namespaced scopes were implemented in #735. They do not work the way I expect.

To Reproduce
Add the following to the spec for namespaced scopes:

it "creates identical queries" do
  expect(MultipleNamespaced.car_unsold.all.to_sql == MultipleNamespaced.unsold.all.to_sql).to be_truthy
  expect(MultipleNamespaced.car_sold.all.to_sql == MultipleNamespaced.sold.all.to_sql).to be_truthy
end

The spec will fail, because the non-namespaced query is:

SELECT "multiple_namespaceds".* FROM "multiple_namespaceds" WHERE "multiple_namespaceds"."status" = 'unsold'

While the namespaced query is:

SELECT "multiple_namespaceds".* FROM "multiple_namespaceds" WHERE "multiple_namespaceds"."status" = 'car_unsold'

Expected behavior
The namespaced query should not be testing a different status value. I do not expect the status values stored in the database to be namespaced.

[kranzky]

I think the fix here would be for create_scope and aasm_create_scope to accept separate scope_name and state_name arguments. For example, the AR implementation might look like this:

conditions = { aasm(state_machine_name).attribute_name => state_name.to_s }
class_eval do
  scope scope_name, lambda { where(table_name => conditions) }
end

Instead of this:

conditions = { aasm(state_machine_name).attribute_name => scope_name.to_s }
class_eval do
  scope scope_name, lambda { where(table_name => conditions) }
end

[kranzky]

See PR #823