Rake and bundle exec rake

 Updated the rake file to use `bundle exec rspec`
 Added the comment to the readme about possibly having to use bundle exec rake
 Updated the Gemfile and Gemfile.lock to include rake

Gemfile

@@ -1,5 +1,6 @@
 source :rubygems
 
+gem 'rake'
 gem 'rspec'
 gem 'guard'
 gem 'guard-rspec'

Gemfile.lock

@@ -6,6 +6,7 @@ GEM
       thor (~> 0.14.6)
     guard-rspec (0.4.0)
       guard (>= 0.4.0)
+    rake (0.9.2)
     rspec (2.6.0)
       rspec-core (~> 2.6.0)
       rspec-expectations (~> 2.6.0)
@@ -22,4 +23,5 @@ PLATFORMS
 DEPENDENCIES
   guard
   guard-rspec
+  rake
   rspec

README.md

@@ -163,6 +163,8 @@ Executing `bundle ` will take care of installing all the remaining gems that thi
 The tests for this project are written in a Ruby test library named [RSpec](https://www.relishapp.com/rspec).
 
     rake
+
+NOTE: If rake fails to work you may have to execute the command: `bundle exec rake`
 
 ### 4. Setup a guard
 

Rakefile

@@ -2,5 +2,5 @@
 task :default => :spec
 
 task :spec do
-  system "rspec -c spec/*_spec.rb"
+  system "bundle exec rspec -c spec/*_spec.rb"
 end