added test in speciesTest for props dictionary attribute of Species.
added test in speciesTest for props dictionary attribute of Species.

testing if props attribute is a dictionary, and if dictionary entries
are properly stored.

nyee/RMG-Py,nyee/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,chatelak/RMG-Py,comocheng/RMG-Py,comocheng/RMG-Py,enochd/RMG-Py,nickvandewiele/RMG-Py,enochd/RMG-Py