disable session_secret for Sinatra::Application in development mode (…

…makes sessions usable out of the box with shotgun)

lib/sinatra/base.rb

@@ -1476,6 +1476,7 @@ class Application < Base
     set :logging, Proc.new { ! test? }
     set :method_override, true
     set :run, Proc.new { ! test? }
+    set :session_secret, Proc.new { super() unless development? }
 
     def self.register(*extensions, &block) #:nodoc:
       added_methods = extensions.map {|m| m.public_instance_methods }.flatten