Rails: Help with rake aborted error! - ruby-on-rails

Question

I have been trying to run the rake db:migrate command but it ain't working. I uninstalled and installed the gem but no luck. I read somewhere the o.9 wasn't stable and that 0.8.7 was ok. I tried it but I got an error also..
For now the error is
Fayimora-Femi-Baloguns-MacBook-Pro:sample_app fayimora$ bundle exec rake db:migrate
/Library/Ruby/Gems/1.8/gems/bundler-1.0.15/lib/bundler/runtime.rb:136: warning: Insecure world writable dir /usr/local in PATH, mode 040777
/Library/Ruby/Gems/1.8/gems/bundler-1.0.15/lib/bundler/runtime.rb:136: warning: Insecure world writable dir /usr/local in PATH, mode 040777
(in /Users/fayimora/Sites/rails_projects/sample_app)
DEPRECATION WARNING: config.generators in Rails::Railtie is deprecated. Please use config.app_generators instead. (called from /Users/fayimora/Sites/rails_projects/sample_app/config/application.rb:12)
DEPRECATION WARNING: config.generators in Rails::Railtie is deprecated. Please use config.app_generators instead. (called from /Users/fayimora/Sites/rails_projects/sample_app/config/application.rb:12)
rake aborted!
undefined method `prerequisites' for nil:NilClass
/Users/fayimora/Sites/rails_projects/sample_app/Rakefile:7
(See full trace by running task with --trace)
My gem list is
Fayimora-Femi-Baloguns-MacBook-Pro:sample_app fayimora$ bundle
Using rake (0.8.7)
Using ZenTest (4.5.0)
Using multi_json (1.0.3)
Using activesupport (3.1.0.rc4)
Using bcrypt-ruby (2.1.4)
Using builder (3.0.0)
Using i18n (0.6.0)
Using activemodel (3.1.0.rc4)
Using erubis (2.7.0)
Using rack (1.3.1)
Using rack-cache (1.0.2)
Using rack-mount (0.8.1)
Using rack-test (0.6.0)
Using hike (1.1.0)
Using tilt (1.3.2)
Using sprockets (2.0.0.beta.10)
Using tzinfo (0.3.29)
Using actionpack (3.1.0.rc4)
Using mime-types (1.16)
Using polyglot (0.3.1)
Using treetop (1.4.9)
Using mail (2.3.0)
Using actionmailer (3.1.0.rc4)
Using arel (2.1.3)
Using activerecord (3.1.0.rc4)
Using activeresource (3.1.0.rc4)
Using autotest (4.4.6)
Using sys-uname (0.8.5)
Using autotest-fsevent (0.2.4)
Using autotest-growl (0.2.9)
Using autotest-rails-pure (4.1.2)
Using bundler (1.0.15)
Using coffee-script-source (1.1.1)
Using execjs (1.2.0)
Using coffee-script (2.2.0)
Using diff-lcs (1.1.2)
Using rack-ssl (1.3.2)
Using rdoc (3.8)
Using thor (0.14.6)
Using railties (3.1.0.rc4)
Using jquery-rails (1.0.12)
Using json (1.5.3)
Using nokogiri (1.5.0)
Using rails (3.1.0.rc4)
Using rspec-core (2.0.0.beta.18)
Using rspec-expectations (2.0.0.beta.18)
Using rspec-mocks (2.0.0.beta.18)
Using rspec (2.0.0.beta.18)
Using webrat (0.7.3)
Using rspec-rails (2.0.0.beta.18)
Using sass (3.1.4)
Using sass-rails (3.1.0.rc.4)
Using spork (0.9.0.rc8)
Using sqlite3 (1.3.3)
Using uglifier (1.0.0)
Contents of Rakefile
#!/usr/bin/env rake
# Add your own tasks in files placed in lib/tasks ending in .rake,
# for example lib/tasks/capistrano.rake, and they will automatically be available to Rake.
# require 'rake/dsl_definition'
require File.expand_path('../config/application', __FILE__)
SampleApp::Application.load_tasks
Please any help would be apprecible. Been having a real hard time learning rails.

Answer 1

The bug with Rake 0.9.2 is fixed. Try using Rake 0.9.2 by adding it to your Gemfile and run
bundle update rake.
I wouldn't use Rails 3.1 RCs besides experimenting or checking your gems for compatibility. Rails 3.0.9 is pretty stable and widely supported.
Edit: https://github.com/rails/rails/issues/1197
The problem is related to a gem not being compatible with Rails 3.1. Try to remove rspec from your Gemfile, bundle install, and run your rake tasks.