--version Prints Both Cap and Rake versions.

Small modification, shows a proof of concept on how we can enable other
top-level command line flags by interacting with Rake (they could make this
easier, to be honest).

Two pending tests for a `--trace` option and a `--format` option, I'm not
fixed on these names, but the notion stands.

lib/capistrano/application.rb

@@ -11,6 +11,14 @@ module Capistrano
       super
     end
 
+    def standard_rake_options
+      Rake::Application.new.standard_rake_options.tap do |sra|
+        sra[sra.index { |opt| opt[0] == "--version" }][3] = lambda do |value|
+          puts "Capistrano Version: #{Capistrano::VERSION} (Rake Version: #{RAKEVERSION})"
+        end
+      end
+    end
+
     def load_rakefile
       @name = 'cap'
       super

spec/lib/capistrano/application_spec.rb

@@ -0,0 +1,53 @@
+require 'spec_helper'
+
+describe Capistrano::Application do
+
+  it "provides a --trace option which enables SSHKit/NetSSH trace output"
+
+  it "provides a --format option which enables the choice of output formatting"
+
+  it "overrides the rake method, but still prints the rake version" do
+    out, _ = capture_io do
+      flags '--version', '-V'
+    end
+    out.should match(/\bCapistrano Version\b/)
+    out.should match(/\b#{Capistrano::VERSION}\b/)
+    out.should match(/\bRake Version\b/)
+    out.should match(/\b#{RAKEVERSION}\b/)
+  end
+
+  def flags(*sets)
+    sets.each do |set|
+      ARGV.clear
+      @exit = catch(:system_exit) { command_line(*set) }
+    end
+    yield(subject.options) if block_given?
+  end
+
+  def command_line(*options)
+    options.each { |opt| ARGV << opt }
+    def subject.exit(*args)
+      throw(:system_exit, :exit)
+    end
+    subject.instance_eval do
+      handle_options
+    end
+    subject.options
+  end
+
+  def capture_io
+    require 'stringio'
+
+    orig_stdout, orig_stderr         = $stdout, $stderr
+    captured_stdout, captured_stderr = StringIO.new, StringIO.new
+    $stdout, $stderr                 = captured_stdout, captured_stderr
+
+    yield
+
+    return captured_stdout.string, captured_stderr.string
+  ensure
+    $stdout = orig_stdout
+    $stderr = orig_stderr
+  end
+
+end