title: cant install capybara webkit gem
body: <p>@ubuntu:~$ sudo gem install capybara-webkit -v '0.14.2'
  [sudo] password for jsnow: 
  Building native extensions.  This could take a while...
  ERROR:  Error installing capybara-webkit:
      ERROR: Failed to build gem native extension.</p>
  
  <pre><code>/usr/bin/ruby1.9.1 extconf.rb
  </code></pre>
  
  <p>cd src/ &amp;&amp; ( test -e Makefile.webkit_server || /usr/lib/x86_64-linux-gnu/qt5/bin/qmake /var/lib/gems/1.9.1/gems/capybara-webkit-0.14.2/src/webkit_server.pro -spec linux-g++ -o Makefile.webkit_server ) &amp;&amp; make -f Makefile.webkit_server 
  Project ERROR: Unknown module(s) in QT: webkit
  make: <em>*</em> [sub-src-webkit_server-pro-make_first-ordered] Error 3
  Command 'make' failed</p>
  
  <p>make  clean
  cd src/ &amp;&amp; ( test -e Makefile.webkit_server || /usr/lib/x86_64-linux-gnu/qt5/bin/qmake /var/lib/gems/1.9.1/gems/capybara-webkit-0.14.2/src/webkit_server.pro -spec linux-g++ -o Makefile.webkit_server ) &amp;&amp; make -f Makefile.webkit_server clean
  Project ERROR: Unknown module(s) in QT: webkit
  make: <em>*</em> [sub-src-webkit_server-pro-clean-ordered] Error 3</p>
  
  <p>make
  cd src/ &amp;&amp; ( test -e Makefile.webkit_server || /usr/lib/x86_64-linux-gnu/qt5/bin/qmake /var/lib/gems/1.9.1/gems/capybara-webkit-0.14.2/src/webkit_server.pro -spec linux-g++ -o Makefile.webkit_server ) &amp;&amp; make -f Makefile.webkit_server 
  Project ERROR: Unknown module(s) in QT: webkit
  make: <em>*</em> [sub-src-webkit_server-pro-make_first-ordered] Error 3</p>
  
  <p>make failed, exit code 2</p>
  
  <p>Gem files will remain installed in /var/lib/gems/1.9.1/gems/capybara-webkit-0.14.2 for inspection.
  Results logged to /var/lib/gems/1.9.1/extensions/x86_64-linux/1.9.1/capybara-webkit-0.14.2/gem_make.out</p>