add unit tests for rmg.model.CoreEdgeReactionModel
add unit tests for rmg.model.CoreEdgeReactionModel

methods:
- makeNewSpecies
- makeNewReaction
- inflate

nickvandewiele/RMG-Py,pierrelb/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,nyee/RMG-Py,nickvandewiele/RMG-Py