Add default priority config

lib/coactive/coaction.rb

@@ -3,7 +3,11 @@
 module Coactive
   class Coaction < Struct.new(:coactor, :name, :options)
     def priority
-      options[:priority] || 1 << 63
+      options[:priority]
+    end
+
+    def priority=(val)
+      options[:priority] = val
     end
   end
 end

lib/coactive/coactions.rb

@@ -24,7 +24,9 @@ def []=(base, name, array)
       def coaction(*names, **options)
         base = coactive_config.base_class
         names.each do |name|
-          coactions = Coactions[base, name].to_a + [Coaction.new(self, name, options)]
+          coaction = Coaction.new(self, name, options)
+          coaction.priority ||= coactive_config.default_priority
+          coactions = (Coactions[base, name].to_a + [coaction])
           Coactions[base, name] = coactions.sort_by.with_index { |coaction, i| [coaction.priority, i] }
         end
       end

lib/coactive/config.rb

@@ -9,6 +9,7 @@ class Config
       use_cache: true,
       lookup_superclass_for_object: true,
       lookup_superclass_until: ['ActiveRecord::Base', 'ActiveModel::Base'],
+      default_priority: 1 << 63
     }
 
     attr_accessor :data