volume steps: lollipop implementation [2/2]

This amounts to a complete rewrite of the volume steps Settings
app implementation. Settings is entirely different from the same
in KitKat, thus the ultimate need for a rewrite.

Still, the original author, Meticulus <theonejohnnyd@gmail.com>,
deserves credit for the original volume steps feature. See:
http://review.pac-rom.com/#/c/467 for the kitkat commit.

PS2: just fixing the commit message to match the other in the set.
PS3: Move to PAC settings
PS4: Never mind
PS5: Rebase
PS6: Move to PAC Settings table
PS7: Add a preference category
PS8: Remove unnecessary commented code.

Change-Id: I03f72867de579c7fb8f2932627f89ea2e94c1613
Merge "volume steps: lollipop implementation [2/2]" into pac-5.0