Error running setup, should add one step to README

[ejakubowski]

Hi, I was attempting to get wallop working on my server but the bundle install in the setup/script was failing.

/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:513:in `block in try_link0'
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tmpdir.rb:88:in `mktmpdir'
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:510:in `try_link0'
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:534:in `try_link'
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:620:in `block in try_ldflags'
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:613:in `with_ldflags'
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:619:in `try_ldflags'
        from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:1725:in `pkg_config'
        from extconf.rb:65:in `pkg_config_wrapper'
        from extconf.rb:92:in `<main>'

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Users/ejakubowski/wallop/vendor/gems/ruby/2.0.0/extensions/universal-darwin-14/2.0.0/eventmachine-1.2.0.1/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /Users/ejakubowski/wallop/vendor/gems/ruby/2.0.0/gems/eventmachine-1.2.0.1 for inspection.
Results logged to /Users/ejakubowski/wallop/vendor/gems/ruby/2.0.0/extensions/universal-darwin-14/2.0.0/eventmachine-1.2.0.1/gem_make.out

An error occurred while installing eventmachine (1.2.0.1), and Bundler cannot continue.
Make sure that `gem install eventmachine -v '1.2.0.1'` succeeds before bundling.

Based on the errors I installed the xcode command line tools with the following command:

xcode-select --install

After installing that the error went away and setup worked. I'm running on a Mac Yosemite. Thanks!