Edge Refinement by Depth Connectivity

Refine edges based on depth connectivity.
In order to take continuity into account, it run RANSAC and remove outliners.

* before
![screenshot_from_2014-08-27 23 24 20](https://cloud.githubusercontent.com/assets/40454/4061197/43b79e2a-2df6-11e4-8ce5-5f3a0639936e.png)

* after
![screenshot_from_2014-08-27 23 23 57](https://cloud.githubusercontent.com/assets/40454/4061196/43ae62c4-2df6-11e4-843a-15cdf123f38b.png)