Rename railties/bin to railties/exe

That will match the new Bundler executables convention.
Bundler Blog Post: http://bundler.io/blog/2015/03/20/moving-bins-to-exe.html
Also updated the necessary tests.

guides/source/initialization.md

@@ -34,7 +34,7 @@ Launch!
 Let's start to boot and initialize the app. A Rails application is usually
 started by running `rails console` or `rails server`.
 
-### `railties/bin/rails`
+### `railties/exe/rails`
 
 The `rails` in the command `rails server` is a ruby executable in your load
 path. This executable contains the following lines:
@@ -45,7 +45,7 @@ load Gem.bin_path('railties', 'rails', version)
 ```
 
 If you try out this command in a Rails console, you would see that this loads
-`railties/bin/rails`. A part of the file `railties/bin/rails.rb` has the
+`railties/exe/rails`. A part of the file `railties/exe/rails.rb` has the
 following code:
 
 ```ruby

railties/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Rename `railties/bin` to `railties/exe` to match the new Bundler executables convention.
+    
+    *Islam Wazery*
+ 
 *   Print `bundle install` output in `rails new` as soon as it's available
 
     Running `rails new` will now print the output of `bundle install` as

railties/railties.gemspec

@@ -15,10 +15,10 @@ Gem::Specification.new do |s|
   s.email    = 'david@loudthinking.com'
   s.homepage = 'http://www.rubyonrails.org'
 
-  s.files        = Dir['CHANGELOG.md', 'README.rdoc', 'RDOC_MAIN.rdoc', 'bin/**/*', 'lib/**/{*,.[a-z]*}']
+  s.files        = Dir['CHANGELOG.md', 'README.rdoc', 'RDOC_MAIN.rdoc', 'exe/**/*', 'lib/**/{*,.[a-z]*}']
   s.require_path = 'lib'
 
-  s.bindir      = 'bin'
+  s.bindir      = 'exe'
   s.executables = ['rails']
 
   s.rdoc_options << '--exclude' << '.'

railties/test/isolation/abstract_unit.rb

@@ -322,7 +322,7 @@ Module.new do
   environment = File.expand_path('../../../../load_paths', __FILE__)
   require_environment = "-r #{environment}"
 
-  `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/bin/rails new #{app_template_path} --skip-gemfile --no-rc`
+  `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/exe/rails new #{app_template_path} --skip-gemfile --no-rc`
   File.open("#{app_template_path}/config/boot.rb", 'w') do |f|
     f.puts "require '#{environment}'"
     f.puts "require 'rails/all'"

railties/test/railties/generators_test.rb

@@ -30,7 +30,7 @@ module RailtiesTests
       if File.exist?("#{environment}.rb")
         require_environment = "-r #{environment}"
       end
-      `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/bin/rails #{cmd}`
+      `#{Gem.ruby} #{require_environment} #{RAILS_FRAMEWORK_ROOT}/railties/exe/rails #{cmd}`
     end
 
     def build_engine(is_mountable=false)