minesweeper: Add parameter to exercise placeholder. Closes #599
minesweeper: Add parameter to exercise placeholder. Closes #599

As discussed in #509

Thanks!

exercism/python,behrtam/xpython,N-Parsons/exercism-python,behrtam/xpython,pheanex/xpython,jmluy/xpython,smalley/python,mweb/python,pheanex/xpython,exercism/python,exercism/xpython,smalley/python,mweb/python,exercism/xpython,jmluy/xpython,N-Parsons/exercism-python