Redirect user to show expense details

Upon clicking on the expense in the ExpandableExpense
Activity the user will be redirected to the show
ExpenseActivity with details about the expense and
buttons for either deleting or editing an expense.

-pass the expense that the user has chosen in Expandable
ExpenseActivity to ShowExpenseActivity.
-implement a method getExpenseBasedOnId that gets an returns
an expense by passing it Expense's id
-implement an onChildClickListener interface in the Expandable
ExpenseActivity