Explicitly extract help from Options object [Fixes #381]

Without this, when the default implementation of puts on ruby-1.9.2
tries to call .to_ary on the options object, you get:

ArgumentError: no id given
gems/ruby-1.9.2-p290@pry/gems/slop-2.4.2/lib/slop.rb:705:in `method_missing'

lib/pry/default_commands/input.rb

@@ -28,7 +28,7 @@ class Pry
           USAGE
 
           opt.on :h, :help, "This message." do
-            output.puts opt
+            output.puts opt.help
           end
         end
 
@@ -74,7 +74,7 @@ class Pry
           opt.on :f, "file", 'The file to replay in context.', true
           opt.on :o, "open", 'When used with the -m switch, it plays the entire method except the last line, leaving the method definition "open". `amend-line` can then be used to modify the method.'
           opt.on :h, :help, "This message." do
-            output.puts opt
+            output.puts opt.help
           end
         end
 

lib/pry/default_commands/introspection.rb

@@ -57,7 +57,7 @@ class Pry
           opt.on :l, "line-numbers", "Show line numbers."
           opt.on :f, :flood, "Do not use a pager to view text longer than one screen."
           opt.on :h, :help, "This message." do
-            output.puts opt
+            output.puts opt.help
           end
         end
 
@@ -111,7 +111,7 @@ class Pry
           opt.on :n, :"no-reload", "Don't automatically reload the edited code"
           opt.on :r, :reload, "Reload the edited code immediately (default for ruby files)"
           opt.on :h, :help, "This message." do
-            output.puts opt
+            output.puts opt.help
           end
         end
         next if opts.present?(:help)
@@ -214,7 +214,7 @@ class Pry
           opt.on "no-jump", "Do not fast forward editor to first line of method."
           opt.on :p, :patch, "Instead of editing the method's file, try to edit in a tempfile and apply as a monkey patch."
           opt.on :h, :help, "This message." do
-            output.puts opt
+            output.puts opt.help
           end
         end
 

lib/pry/default_commands/shell.rb

@@ -74,7 +74,7 @@ class Pry
           opt.on :t, :type, "The specific file type for syntax higlighting (e.g ruby, python)", true, :as => Symbol
           opt.on :f, :flood, "Do not use a pager to view text longer than one screen."
           opt.on :h, :help, "This message." do
-            output.puts opt
+            output.puts opt.help
           end
         end
 

lib/pry/helpers/options_helpers.rb

@@ -22,7 +22,7 @@ class Pry
           yield opt
 
           opt.on :h, :help, "This message" do
-            output.puts opt.to_s
+            output.puts opt.help
             throw :command_done
           end
         end