Merge pull request #7 from Kaggle-Practice-Group/fb-code-cleanup-2

Fb code cleanup 2
I consolidated some more code and added a switch to turn the validation set on and off.

- Created boolean 'use.validation' which automatically allows for use of a validation set, or not.

- When 'use.validation' is TRUE, data is split accordingly: 45% training, 30% validation, & 25% testing. When it is false: 75% training, & 25% testing.

- Fixed a bug where ANN in-sample accuracy was being incorrectly reported.

- All models' in-sample accuracy is now dynamically calculated, and requires less code.

- The formula used for training has now been pulled out into its own variable, so it can now be set once, and applied to all models.
Fixed the formula definition.
Merge branch 'fb-code-cleanup-3' of https://github.com/Kaggle-Practice-Group/Kaggle_Titanic into fb-code-cleanup-3