added master/detail flow template for trainee list
refactored
added implementation for trainee_list. works with trainer API now.
added API handler - supports POST and GET with or without authentication. will add comments soon.
added some javadoc for APIHandler
changed TraineeListFragment to match change in Trainer API database.
Merge pull request #4 from csci477-team4/trainee_list

Trainee List works with Trainer API, also added APIHandler for  HTTP requests