e68c06e1 strip unecessary names from exercise notebooks

exercises/Diffusion_serial.ipynb

exercises/NumPy_Exercise.ipynb

exercises/Parallel_Exercise.ipynb

exercises/Python-refresher-Exercise.ipynb

exercises/_solutions/Diffusion_serial_withsolution.ipynb

exercises/_solutions/NumPy_Exercise_withsolution.ipynb

exercises/_solutions/Parallel_Exercise_withsolution.ipynb

.../_solutions/Python-refresher-Exercise-with-solution.ipynb