title: how to install ruby-netcdf with ruby 2.2?
body: <p>When I try to install the gem ruby-netcdf on Fedora I got the following.
  Using ruby 2.2 and rvm (also tried ruby 1.8.7 but narray gem doesn t build properly) 
  Any help is welcome, thanks.</p>
  
  <pre><code>$ gem install ruby-netcdf
  
  Building native extensions.  This could take a while...
  ERROR:  Error installing ruby-netcdf:
      ERROR: Failed to build gem native extension.
  
  
   /home/user/.rvm/rubies/ruby-2.2.0/bin/ruby -r ./siteconf20150128-5543-74d90a.rb extconf.rb
  *** 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}/lib
      --with-make-prog
      --without-make-prog
      --srcdir=.
      --curdir
      --ruby=/home/user/.rvm/rubies/ruby-2.2.0/bin/$(RUBY_BASE_NAME)
  extconf.rb:4:in `&lt;main&gt;': uninitialized constant Gem::GemPathSearcher (NameError)
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /home/user/.rvm/gems/ruby-2.2.0@testnetcdf/gems/ruby-netcdf-0.6.6.1 for inspection.
  Results logged to /home/user/.rvm/gems/ruby-2.2.0@testnetcdf/extensions/x86_64-linux/2.2.0/ruby-netcdf-0.6.6.1/gem_make.out
  </code></pre>