def initialize(connectable = ActiveRecord::Base)
        @connectable = connectable
      end
Creates an instance of the Scenic Postgres adapter.

This is the default adapter for Scenic. Configuring it via
{Scenic.configure} is not required, but the example below shows how one
would explicitly set it.

@param [#connection] connectable An object that returns the connection
for Scenic to use. Defaults to `ActiveRecord::Base`.

@example
Scenic.configure do |config|
config.database = Scenic::Adapters::Postgres.new
end