revert removed directories

The pull request by k-okada is already merged into hydro-devel, but not merged into groovy-devel
https://github.com/ros-perception/perception_pcl/pull/11

This pull request not only includes the diff of the k-okada pull request but also reverts `pcl_nodelets.xml`.

`pcl_nodelets.xml` is required to be reverted in order to use the nodelet classes from other ros launch files.