title: "sh: make: command not found" when running "$ bundle" after adding redcarpet gem to Rails app
body: <p>I'm getting the following when running "$ bundle" after adding "gem 'redcarpet'" to Gemfile:</p>
  
  <pre><code>$ bundle
  ...
  Using paperclip (2.3.11) 
  Using passenger (3.0.7) 
  Installing redcarpet (1.17.2) with native extensions /Users/robs/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:551:in `rescue in block in build_extensions': ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)
  
      /Users/robs/.rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb 
  creating Makefile
  
  make
  sh: make: command not found
  
  Gem files will remain installed in /Users/robs/.rvm/gems/ruby-1.9.2-p180@rails-3.0/gems/redcarpet-1.17.2 for inspection.
  Results logged to /Users/robs/.rvm/gems/ruby-1.9.2-p180@rails-3.0/gems/redcarpet-1.17.2/ext/redcarpet/gem_make.out
  from /Users/robs/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:529:in `block in build_extensions'
  from /Users/robs/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:504:in `each'
  from /Users/robs/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:504:in `build_extensions'
  from /Users/robs/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:180:in `install'
  from /Users/robs/.rvm/gems/ruby-1.9.2-p180@global/gems/bundler-1.0.15/lib/bundler/source.rb:101:in `block in install'
  from /Users/robs/.rvm/gems/ruby-1.9.2-p180@global/gems/bundler-1.0.15/lib/bundler/rubygems_integration.rb:78:in `preserve_paths'
  ...
  from /Users/robs/.rvm/gems/ruby-1.9.2-p180@global/gems/bundler-1.0.15/bin/bundle:13:in `&lt;top (required)&gt;'
  from /Users/robs/.rvm/gems/ruby-1.9.2-p180@rails-3.0/bin/bundle:19:in `load'
  from /Users/robs/.rvm/gems/ruby-1.9.2-p180@rails-3.0/bin/bundle:19:in `&lt;main&gt;'
  </code></pre>
  
  <p><a href="https://gist.github.com/1058833" rel="nofollow noreferrer">Full gist here.</a></p>
  
  <p>I am using rvm with different gemsets. This application is using the @rails-3.0 gemset. <a href="https://stackoverflow.com/questions/6286021/using-passenger-to-run-both-rails-3-0-and-rails-3-1-app-using-different-rvm-gems">Here is my previous question</a> regarding that setup.</p>
  
  <p>I noticed the "Installing redcarpet (1.17.2)..." line includes "/Users/robs/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/<strong>1.9.1</strong>/rubygems/installer.rb". Is this part of the problem? How can I get this to install?</p>
  
  <p>Thanks.</p>