The idea of multiple processes serving as home was unfeasible.
- Revert "Allow for more than one home app." commit
e428a7f662f109a5f2015008e3161df23932483e.
- Assign ActivityManagerService.mHomeProcess to the process of the
root activity of the home task.
Addresses bug 10342471.
Change-Id: Ifb494626107d24de1306e320a18206d5b176a7c0