Display ProgressBar after submitting a pickup.

Calling AsyncTask.get() from the UI thread will freeze the UI thread.
Instead, move those operations to the onPostExecute() method.
Show the ProgressBar when getting employee list.

Same issues as @7054fc864031ee4c4b628bbc4eec9d96c5202c39
Move more data processing to background threads.

Also some cleaning of duplicate/unused code.