Add abstract cache layer

app/Core/Cache/CacheInterface.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace Core\Cache;
+
+/**
+ * Cache Interface
+ *
+ * @package  cache
+ * @author   Frederic Guillot
+ */
+interface CacheInterface
+{
+    /**
+     * Save a new value in the cache
+     *
+     * @access public
+     * @param  string  $key
+     * @param  string  $value
+     */
+    public function set($key, $value);
+
+    /**
+     * Fetch value from cache
+     *
+     * @access public
+     * @param  string  $key
+     * @return mixed            Null when not found, cached value otherwise
+     */
+    public function get($key);
+
+    /**
+     * Clear all cache
+     *
+     * @access public
+     */
+    public function flush();
+
+    /**
+     * Remove cached value
+     *
+     * @access public
+     * @param  string  $key
+     */
+    public function remove($key);
+}