change cell back to regular module
clean up some formatting
fix global problem in grid
expose cells array for testing
rename MyApp.cell to MyApp.createCell
add tests for retrieving cells array from grid
refactor cell

shouldn't care what mark character it gets
make sure mark is a string
use only the first character of the string
cleanup

added semicolons, etc.
start tests for detecting win
remove cell exceptions

return null instead of throwing exception
change grid to createGrid
add test for formatWinningRow, remove reset
moved formatting from cell to grid

do I still need a cell class?