db:migrate command not working while installing CommunityEngine, a ruby on rails plugin

I started with creating an app : rails new appfog -d mysql as i have newest version of rails install i have to edit my gemfile so I Open gemfile, add gem 'community_engine', '~> 3.0.0' and set rails and sass-rails to gem 'rails', '~> 4.0.0' and gem 'sass-rails', '~> 4.0.0'.

Then i created a new application_config.rb and add configatron.community_name = "appfog"

I delete gemfile.lock and run bundle install --binstubs. It says next to run bin/rake community_engine:install:migrations.

And finally when i run bin/rake db:migrate , it gave me bunch of errors

rake aborted!
NoMethodError: undefined method `configure' for #<Appfog::Application:0x007f9daa9a7f00>
/Users/sarthak/Desktop/Appfog/config/environments/development.rb:1:in `<top (required)>'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `require'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `block in require'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:213:in `load_dependency'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `require'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/engine.rb:591:in `block (2 levels) in <class:Engine>'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/engine.rb:590:in `each'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/engine.rb:590:in `block in <class:Engine>'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:30:in `instance_exec'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:30:in `run'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:55:in `block in run_initializers'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:44:in `each'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:44:in `tsort_each_child'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:54:in `run_initializers'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/application.rb:215:in `initialize!'
/Users/sarthak/Desktop/Appfog/config/environment.rb:5:in `<top (required)>'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `require'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `block in require'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:213:in `load_dependency'
/Library/Ruby/Gems/2.0.0/gems/activesupport-4.0.0/lib/active_support/dependencies.rb:228:in `require'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/application.rb:189:in `require_environment!'
/Library/Ruby/Gems/2.0.0/gems/railties-4.0.0/lib/rails/application.rb:249:in `block in run_tasks_blocks'
Tasks: TOP => db:migrate => environment
(See full trace by running task with --trace)

Please help me in finding my mistake. I have already checked all the forums but couldn't get any possible solution.