[skip travis] EG: Add new example notebook for semantic segmentation functionality (#167)

- Add new example notebook based on the semantic segmentation functionality. 
In this notebook I tried to show two things:
1- How easy it is to to use pretrained segmentation models
2- How a user can use their own segmentation model in the process.

Co-authored by: @mostafajahanifar

Author: mostafajahanifar