Merge pull request #167 from tmkpath/dev

Finally make derived model-object Link consistent with the previous
Add new objects for RampMeters and IntersectionPlanSets as well as updated tests
clean up setter/getters to use super`:
Cleanup from code reviews
Merge pull request #168 from MauriceManning/dev

Add new objects for RampMeters and IntersectionPlanSets as well as updated tests
Added method to IntersectionPlanSet to get a SignalPlanSet by its ID, and
modified the test to call it.

Changes to be committed:
modified:   src/main/java/edu/berkeley/path/model_objects/scenario/IntersectionPlanSet.java
modified:   src/test/java/edu/berkeley/path/model_objects/scenario/IntersectionPlanSetTest.java