fixes scope bug on point_pose_extraction

[furushchev]

This PR fixes some bugs on point_pose_extraction node.
Since the ObjectDetection_agg topic here was just an alias of ObjectDetection and it was not aggregated, I created an aggregator. (see jsk-ros-pkg/jsk_common_msgs#24 )

[k-okada]

if you intend to use this node with jsk-ros-pkg/jsk_common_msgs#24, plese update the https://github.com/jsk-ros-pkg/jsk_recognition/blob/master/jsk_perception/launch/point_pose_extractor_sample.launch

but to keep backward compatibility and avoid confusion, another solution is to publish _agg from this node with more slower rate. Not sure which is better.

[YutoUchimi]

For backward compatibility, I reverted the commit in which publishing of ObjectDetection_agg is removed.
If we need slower rate for _agg, let's make another PR.