Added main interfaces to their own files

This will allow people to actually use the interfaces.

proposed/PSR/Cache/CacheFactory.php

@@ -0,0 +1,12 @@
+
+namespace PSR\Cache;
+
+interface CacheFactory 
+{
+    /**
+     *
+ ÊÊÊ * @param string $key
+ ÊÊÊ * @return CacheItem
+     */
+    function getCache($key);
+}

proposed/PSR/Cache/CacheItem.php

@@ -0,0 +1,30 @@
+namespace PSR\Cache;
+
+interface CacheItem 
+{
+    /**
+     *
+     * @return mixed
+     */ÊÊÊÊÊÊÊ
+    function get();
+
+    /**
+     *
+     * @param mixed $value
+     * @param int $ttl
+     * @return bool
+     */ ÊÊÊÊÊÊÊ
+    function set($value, $ttl = null);
+
+    /**
+     *
+     * @return bool
+     */
+    function isMiss();
+
+    /**
+     *
+     * @return mixed
+     */
+    function clear();
+}