title: Cocoapods : spec.prefix_header_contents does not work
body: <p>Here is my podspec :</p>
  
  <pre><code>Pod::Spec.new do |s|
    s.name         = "MyCBDLumberJack"
    s.version      = "0.0.1"
    s.source       = { :git =&gt; 'https://me@bitbucket.org/me/mycbdlumberjack.git', 
                      :tag =&gt;  "#{s.version}" }
    s.source_files  = 'MyCBDLumberJack/My Lumberjack/**/*.{h,m}'
    s.public_header_files = 'MyCBDLumberJack/**/InitializationCocoaLumberjack.h'
    s.resource  = "MyCBDLumberJack/Help_MyCBDLumberJack.rtfd"
    s.ios.platform   = :ios, '5.0'
    s.osx.platform   = :osx, '10.7'
    s.requires_arc = true
    s.osx.framework = 'AppKit'
    s.ios.framework = 'UIKit'
    s.prefix_header_contents = '#import "DDLog.h"'
    s.dependency 'CocoaLumberjack', '~&gt;1.8'
  end
  </code></pre>
  
  <p>But, I don't see any result for it. The <code>#import "DDLog.h"</code> does not appear in <code>Pods-MyCBDLumberJack-prefix.pch</code>.</p>
  
  <p>Am I looking at the wrong place?</p>
  
  <p>PS: it seems that the line is included when linting but is not included when I include the pod in a project...</p>