title: Error installing charlock_holmes : Error installing GITLAB
body: <p>I am trying to install GITLAB. I get this error executing "<code>sudo gem install charlock_holmes --version '0.6.9'</code>" (section <a href="https://github.com/gitlabhq/gitlabhq/blob/4-2-stable/doc/install/installation.md#install-gems">Install Gems</a>) </p>
  
  <pre><code>GEOGIT:/geogit/Administrative_Tools # sudo gem install charlock_holmes --version '0.6.9'
  Building native extensions.  This could take a while...
  ERROR:  Error installing charlock_holmes:
          ERROR: Failed to build gem native extension.
  
          /usr/bin/ruby1.9 extconf.rb
  checking for main() in -licui18n... no
  which: no brew in (/usr/sbin:/bin:/usr/bin:/sbin)
  checking for main() in -licui18n... no
  
  ***************************************************************************************
  *********** icu required (brew install icu4c or apt-get install libicu-dev) ***********
  ***************************************************************************************
  *** extconf.rb failed ***
  Could not create Makefile due to some reason, probably lack of
  necessary libraries and/or headers.  Check the mkmf.log file for more
  details.  You may need configuration options.
  
  Provided configuration options:
          --with-opt-dir
          --without-opt-dir
          --with-opt-include
          --without-opt-include=${opt-dir}/include
          --with-opt-lib
          --without-opt-lib=${opt-dir}/
          --with-make-prog
          --without-make-prog
          --srcdir=.
          --curdir
          --ruby=/usr/bin/ruby1.9
          --with-icu-dir
          --without-icu-dir
          --with-icu-include
          --without-icu-include=${icu-dir}/include
          --with-icu-lib
          --without-icu-lib=${icu-dir}/
          --with-icui18nlib
          --without-icui18nlib
          --with-icui18nlib
          --without-icui18nlib
  
  Gem files will remain installed in /usr/lib64/ruby/gems/1.9.1/gems/charlock_holmes-0.6.9 for inspection.
  Results logged to /usr/lib64/ruby/gems/1.9.1/gems/charlock_holmes-0.6.9/ext/charlock_holmes/gem_make.out
  </code></pre>
  
  <p>Someone, can help me debug those logs and error?</p>