Move exceptions to new file.

lib/geocoder.rb

 require "geocoder/configuration"
 require "geocoder/calculations"
+require "geocoder/exceptions"
 require "geocoder/cache"
 require "geocoder/request"
 require "geocoder/models/active_record"
@@ -67,11 +68,6 @@ module Geocoder
   end
 
 
-  # exception classes
-  class Error < StandardError; end
-  class ConfigurationError < Error; end
-
-
   private # -----------------------------------------------------------------
 
   ##

lib/geocoder/exceptions.rb

+module Geocoder
+
+  class Error < StandardError
+  end
+
+  class ConfigurationError < Error
+  end
+end