title: Can't install laravel installer via composer
body: <p>I'm trying to install laravel installer with the composer on my Ubuntu PC, but I get this error during the installation. `Your requirements could not be resolved to an installable set of packages.</p>
  
  <pre><code>  Problem 1
      - laravel/installer v1.4.1 requires ext-zip * -&gt; the requested PHP extension zip is missing from your system.
      - laravel/installer v1.4.0 requires ext-zip * -&gt; the requested PHP extension zip is missing from your system.
      - Installation request for laravel/installer ^1.4 -&gt; satisfiable by laravel/installer[v1.4.0, v1.4.1].
  
    To enable extensions, verify that they are enabled in those .ini files:
      - /etc/php/7.0/cli/php.ini
      - /etc/php/7.0/cli/conf.d/10-opcache.ini
      - /etc/php/7.0/cli/conf.d/10-pdo.ini
      - /etc/php/7.0/cli/conf.d/20-calendar.ini
      - /etc/php/7.0/cli/conf.d/20-ctype.ini
      - /etc/php/7.0/cli/conf.d/20-exif.ini
      - /etc/php/7.0/cli/conf.d/20-fileinfo.ini
      - /etc/php/7.0/cli/conf.d/20-ftp.ini
      - /etc/php/7.0/cli/conf.d/20-gettext.ini
      - /etc/php/7.0/cli/conf.d/20-iconv.ini
      - /etc/php/7.0/cli/conf.d/20-json.ini
      - /etc/php/7.0/cli/conf.d/20-phar.ini
      - /etc/php/7.0/cli/conf.d/20-posix.ini
      - /etc/php/7.0/cli/conf.d/20-readline.ini
      - /etc/php/7.0/cli/conf.d/20-shmop.ini
      - /etc/php/7.0/cli/conf.d/20-sockets.ini
      - /etc/php/7.0/cli/conf.d/20-sysvmsg.ini
      - /etc/php/7.0/cli/conf.d/20-sysvsem.ini
      - /etc/php/7.0/cli/conf.d/20-sysvshm.ini
      - /etc/php/7.0/cli/conf.d/20-tokenizer.ini
    You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.
  `
  </code></pre>
  
  <p>The error appears then I use this comment: </p>
  
  <pre><code>composer global require "laravel/installer"
  </code></pre>