Fix elapsed time formatting.

We should extend DateUtils to provide this kind of elapsed time
formatting via icu4c, but for now let's at least fix our
arithmetic.

Bug: https://code.google.com/p/android/issues/detail?id=61479
Change-Id: I6c087dbb9fdbff0a21d9243d239126fee180454c
Fix null pointer exceptions in NetworkPolicyEditor

This upload fixes a null pointer exception issue.
After this fix the modified methods return
their corresponding default values instead of null.

Change-Id: Idb94f8b808b8dd18be5e3fc92cc5560ce0f81c4f
Fix blacklist preferences fragment transition for tablets.

Change-Id: Iecde099b111ae31c8e11ce366d9d06d965029ed7
Fix confusing warning dialog behaviour.

The settings app closing when pressing back while the dialog is shown or
clicking outside of the dialog was confusing for the user. Instead, make
sure the user has to acknowledge the dialog.

Change-Id: I8ffdf6a2ede8b67176fd22a13d7046a707b52b89