title: Can't install Mailgun library on Windows with composer
body: <p>I have been trying to install mailgun library in my localhost using composer. I wrote in the command prompt the following commands:</p>
  
  <p><code>php composer require mailgun/mailgun-php:~1.3</code></p>
  
  <p>it gives me error as <code>Could not open input file: composer</code></p>
  
  <p>then I tried removing the <code>php</code> at the beginning of the previous command :</p>
  
  <p><code>composer require mailgun/mailgun-php:~1.3</code></p>
  
  <p>it shows:</p>
  
  <pre><code>./composer.json has been updated
  Loading composer repositories with package information
  Updating dependencies (including require-dev)
  Your requirements could not be resolved to an installable set of packages.
  
  Problem 1
  - The requested package mailgun/mailgun-php 1.0.0 could not be found.
  Problem 2
  - guzzle/guzzle v3.7.4 requires ext-curl * -&gt; the requested PHP extension cu
  rl is missing from your system.
  - guzzle/guzzle v3.7.3 requires ext-curl * -&gt; the requested PHP extension cu
  rl is missing from your system.
  - guzzle/guzzle v3.7.2 requires ext-curl * -&gt; the requested PHP extension cu
  rl is missing from your system.
  - guzzle/guzzle v3.7.1 requires ext-curl * -&gt; the requested PHP extension cu
  rl is missing from your system.
  - guzzle/guzzle v3.7.0 requires ext-curl * -&gt; the requested PHP extension cu
  rl is missing from your system.
  - Installation request for guzzle/guzzle 3.7.* -&gt; satisfiable by guzzle/guzz
  le[v3.7.0, v3.7.1, v3.7.2, v3.7.3, v3.7.4].
  
  Potential causes:
  - A typo in the package name
  - The package is not available in a stable-enough version according to your min
  imum-stability setting
   see &lt;https://groups.google.com/d/topic/composer-dev/_g3ASeIFlrc/discussion&gt; f
  or more details.
  
  Read &lt;http://getcomposer.org/doc/articles/troubleshooting.md&gt; for further common
  problems.
  
  Installation failed, reverting ./composer.json to its original content.
  </code></pre>
  
  <p>I have been struggling to install mailgun for couple of days, please help me.</p>
  
  <p><strong>Update:</strong></p>
  
  <p>FYI: I am using windows using xampp</p>
  
  <p>composer.phar file details:</p>
  
  <pre><code>{
  "name": "mailgun/mailgun-php",
  "description": "The Mailgun SDK provides methods for all API functions.",
  "require": {
      "guzzle/guzzle": "3.7.*"
  },
  "require-dev": {
      "phpunit/phpunit": "3.7.*"
  },
  "autoload": {
      "psr-0": {
          "Mailgun\\Tests": "tests/",
          "Mailgun": "src/"
      }
  },
  "license": "MIT",
  "authors": [
      {
          "name": "Travis Swientek",
          "email": "travis@mailgunhq.com"
      }
  ],
  "minimum-stability": "stable"
  }
  </code></pre>