Introduce Provider namespace and move Node and Time classes into it

src/Provider/Node/SystemNodeProvider.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace Rhumsaa\Uuid\Provider\Node;
+
+use Rhumsaa\Uuid\Provider\NodeProviderInterface;
+
+class SystemNodeProvider implements NodeProviderInterface
+{
+    public function getNode()
+    {
+        $node = null;
+        $pattern = '/[^:]([0-9A-Fa-f]{2}([:-])[0-9A-Fa-f]{2}(\2[0-9A-Fa-f]{2}){4})[^:]/';
+        $matches = array();
+
+        // Search the ifconfig output for all MAC addresses and return
+        // the first one found
+        if (preg_match_all($pattern, $this->getIfconfig(), $matches, PREG_PATTERN_ORDER)) {
+            $node = $matches[1][0];
+            $node = str_replace(':', '', $node);
+            $node = str_replace('-', '', $node);
+        }
+
+        return $node;
+    }
+
+    /**
+     * Returns the network interface configuration for the system
+     *
+     * @todo Needs evaluation and possibly modification to ensure this works
+     *       well across multiple platforms.
+     * @codeCoverageIgnore
+     * @return string
+     */
+    protected function getIfconfig()
+    {
+        switch (strtoupper(substr(php_uname('a'), 0, 3))) {
+            case 'WIN':
+                $ifconfig = `ipconfig /all 2>&1`;
+                break;
+            case 'DAR':
+                $ifconfig = `ifconfig 2>&1`;
+                break;
+            case 'LIN':
+            default:
+                $ifconfig = `netstat -ie 2>&1`;
+                break;
+        }
+
+        return $ifconfig;
+    }
+}