Update deprecated keyword

tasks/main.yml

@@ -10,7 +10,7 @@
   - name: "Install MemCache"
     apt:
       pkg='{{item}}'
-      state='installed'
+      state='present'
       update_cache=yes
     with_items:
       - php{{ (php_version|default('5.5') == '5.3') | ternary('5','') }}-memcached