Final code check-in for HRI14 TaskGraphLearning project.

First check-in for ICRA14 Graph Exploration project.
Added first implementation of the graph generator with limited testing done. Fixed loading error in EnvironmentEdge where the env_skills vector wasn't being assigned to skills_.
Removed unnecessary checks on EnvironmentEdge prerequisite satisfaction.
Fixed ChainOfClique and CliqueOfChain graph output mechanisms.
Merge branch 'master' of https://github.com/hayesbh/Social-Hierarchical-Learning