add OcludedPlaneEstimator 

estimate the planes which ocluded several reason.
currently just **append** the planes which the user can predefine such as foot print.

* red polygons are the pre-defined polygons (such as footprint)
* blue polygons are the estimated planes from the sensor
* green is the result of the estimation of oclusion. (just appending the near planes)

![screenshot_from_2014-06-03 23_19_01](https://cloud.githubusercontent.com/assets/40454/3161636/c05303b8-eb2d-11e3-8105-946c66551e3a.png)