Add location method to ship_section and build_ship to ship.rb.
Update to ship.rb
Ships sink when all of their sections have been hit.
Ships of 3 sections can be built.
Refactor build_ship and dependencies to be much better.
Ship can build out its sections based on head and tail locations.
Boards can place markers and ship sections at particular grid locations.
Unsaved changes from previous commit.
Refactor Board method to use abtract base class CellContent.
Refactor Board method to use abtract base class CellContent (completed).
A board of any size can be created and will be filled with objects of CellContent class.
Board can generate a tracking grid of which cells have been hit.