title: Installing pg -v 0.17.1
body: <p>I'm using/I want to use Postgresql as database, but when I type "bundle install" or "bundle update", I get this error, what do I do to fix this? :)</p>
  
  <pre><code>    Installing pg (0.17.1) with native extensions 
  Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
  
          /usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby extconf.rb 
  checking for pg_config... no
  No pg_config... trying anyway. If building fails, please try again with
   --with-pg-config=/path/to/pg_config
  checking for libpq-fe.h... no
  Can't find the 'libpq-fe.h header
  *** 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=/usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby
      --with-pg
      --without-pg
      --with-pg-config
      --without-pg-config
      --with-pg_config
      --without-pg_config
      --with-pg-dir
      --without-pg-dir
      --with-pg-include
      --without-pg-include=${pg-dir}/include
      --with-pg-lib
      --without-pg-lib=${pg-dir}/lib
  
  
  Gem files will remain installed in /Users/rsvmrk/.bundler/tmp/22196/gems/pg-0.17.1 for inspection.
  Results logged to /Users/rsvmrk/.bundler/tmp/22196/gems/pg-0.17.1/ext/gem_make.out
  An error occurred while installing pg (0.17.1), and Bundler cannot continue.
  Make sure that `gem install pg -v '0.17.1'` succeeds before bundling.
  </code></pre>
  
  <p>Any suggestions?</p>