title: error running gem install pg -v '0.15.1'
body: <p>Running</p>
  
  <pre><code>gem install pg -v '0.15.1'
  </code></pre>
  
  <p>giving errors:</p>
  
  <blockquote>
    <p>Building native extensions.  This could take a while... ERROR:  Error
    installing pg:    ERROR: Failed to build gem native extension.</p>
  
  <pre><code>    /home/askar/.rvm/rubies/ruby-1.9.3-p429/bin/ruby extconf.rb checking for pg_config... no No pg_config... trying anyway. If
  </code></pre>
    
    <p>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
    <strong>* extconf.rb failed *</strong> 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.</p>
    
    <p>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/askar/.rvm/rubies/ruby-1.9.3-p429/bin/ruby     --with-pg
      --without-pg    --with-pg-dir   --without-pg-dir    --with-pg-include
      --without-pg-include=${pg-dir}/include  --with-pg-lib
      --without-pg-lib=${pg-dir}/lib  --with-pg-config    --without-pg-config
      --with-pg_config    --without-pg_config</p>
    
    <p>Gem files will remain installed in
    /home/askar/.rvm/gems/ruby-1.9.3-p429/gems/pg-0.15.1 for inspection.
    Results logged to
    /home/askar/.rvm/gems/ruby-1.9.3-p429/gems/pg-0.15.1/ext/gem_make.out</p>
  </blockquote>
  
  <p>I'm using</p>
  
  <ol>
  <li>Rails 4.0.0.rc1</li>
  <li>Ruby 1.9.3-p429</li>
  <li>Linux Mint Nadia v 14</li>
  </ol>