Switch to Module#prepend to patch stdlib Logger

instead of older style alias_method chain juggling. We hope this has fewer poor interactions with other things patching Logger as in rudionrails#60. And it's just a more modern cleaner style.

Could be a first step to making this stdlib Logger patching optional, but does not require that.

lib/yell.rb

@@ -134,7 +134,11 @@ def __fetch__( hash, *args )
 require File.dirname(__FILE__) + '/yell/loggable'
 
 # core extensions
-require File.dirname(__FILE__) + '/core_ext/logger'
+require File.dirname(__FILE__) + '/yell/stdlib_log_wrapper'
+
+# Patch stdlib ::Logger
+require 'logger'
+::Logger.prepend(Yell::StdlibLogWrapper)
 
 # register known adapters
 Yell.register :null, Yell::Adapters::Base # adapter that does nothing (for convenience only)

lib/yell/stdlib_log_wrapper.rb

@@ -0,0 +1,12 @@
+module Yell
+  # Module intended to be prepended onto ::Logger
+  module StdlibLogWrapper
+    def level=(level)
+      super(level.is_a?(Yell::Level) ? Integer(level) : level)
+    end
+
+    def add( severity, message = nil, progname = nil, &block )
+      super(Integer(severity), message, progname, &block)
+    end
+  end
+end