Prevent page wrappers from clearing all caches on node insert

Issue:
Page Wrappers clears all caches on node insert for all node types.

Replicate:
Configure xhprof. Add a node of any type. View the function call list and drill down into page_wrappers_node_insert to see its call of drupal_flush_all_caches.

Fix:
Move drupal_flush_all_caches inside of the conditional statement that checks if the current node is a page wrapper.