Fixed Archive Display

Changed from arrayadapter to simplecursoradapter to display the SQL data
on the archive page listview. This now means I can access the row id of
the item clicked making deletions/modifications of entries much more
straightforward.

Added colours.xml, list of w3 colour resources.

Record class now uses a datepicker to get the date of the training
sessions, so the datevalidator was unnecessary and has been removed.