refactoring and cleaning

...va/gov/usgs/earthquake/nshmp/model/ClusterRuptureSet.java

...java/gov/usgs/earthquake/nshmp/model/FaultRuptureSet.java

...ain/java/gov/usgs/earthquake/nshmp/model/FaultSource.java

...main/java/gov/usgs/earthquake/nshmp/model/GridLoader.java

...ain/java/gov/usgs/earthquake/nshmp/model/HazardModel.java

.../gov/usgs/earthquake/nshmp/model/InterfaceRuptureSet.java

src/main/java/gov/usgs/earthquake/nshmp/model/MfdTrees.java

src/main/java/gov/usgs/earthquake/nshmp/model/ModelData.java

...ain/java/gov/usgs/earthquake/nshmp/model/ModelLoader.java

.../java/gov/usgs/earthquake/nshmp/model/SlabRuptureSet.java

.../java/gov/usgs/earthquake/nshmp/model/ZoneRuptureSet.java