Created PyLammps documentation

Based on material presented during MD Workshop at Temple University in
August 2016.

python/examples/pylammps/mpi4py/melt.py

@@ -0,0 +1,10 @@
+from mpi4py import MPI
+from lammps import PyLammps
+
+L = PyLammps()
+L.file('in.melt')
+
+
+if MPI.COMM_WORLD.rank == 0:
+    pe = L.eval("pe")
+    print("Potential Energy:", pe)