Trainee layout

<ul>
<li>Created a new layout to display trainee list in three parts: trainee picture, trainee name, and right arrow picture
<li>Trainee list names are populated by database, pictures are hard coded by position
<li>Pictures -> WorkoutHistoryActivity
<li>Name -> TraineeDetailActivity
<li>Arrow -> MessageActivity
<li>trainee_id is updated in SharedPreferences before starting new activity
</li>