Add an experimental "console" CLI command.

The "console" command drops you into an IRB session in the context of the
Middleman application instance. You can look at configuration, poke around
at the sitemap and data, try out handlers (after calling self.current_path = "foo"), etc.

middleman-core/lib/middleman-core/cli.rb

@@ -87,3 +87,4 @@ require "middleman-core/cli/bundler"
 require "middleman-core/cli/extension"
 require "middleman-core/cli/server"
 require "middleman-core/cli/build"
+require "middleman-core/cli/console"

middleman-core/lib/middleman-core/cli/console.rb

@@ -0,0 +1,46 @@
+# CLI Module
+module Middleman::Cli
+
+  # A thor task for creating new projects
+  class Console < Thor
+    include Thor::Actions
+
+    check_unknown_options!
+
+    namespace :console
+    
+    desc "console [options]", "Start an interactive console in the context of your Middleman application"
+    method_option :environment,
+      :aliases => "-e",
+      :default => ENV['MM_ENV'] || ENV['RACK_ENV'] || 'development',
+      :desc    => "The environment Middleman will run under"
+    method_option :verbose,
+      :type    => :boolean,
+      :default => false,
+      :desc    => 'Print debug messages'
+    def console
+      require "middleman-core"
+      require "irb"
+
+      opts = {
+        :environment => options['environment'],
+        :debug => options['verbose']
+      }
+
+      @app =::Middleman::Application.server.inst do
+        if opts[:environment]
+          set :environment, opts[:environment].to_sym
+        end
+
+        logger(opts[:debug] ? 0 : 1, opts[:instrumenting] || false)
+      end
+
+      # TODO: get file watcher / reload! working in console
+
+      IRB.setup nil
+      IRB.conf[:MAIN_CONTEXT] = IRB::Irb.new.context
+      require 'irb/ext/multi-irb'
+      IRB.irb nil, @app
+    end
+  end
+end