Grumble, nobody likes kibibytes.

All the cool kids are using storage in increments of 1000 instead
of 1024, so find a balance somewhere between the two.  We still round
to nice values like 32GB, 64GB, etc, but we represent them using
kilobytes under the hood.

Test: runtest -x frameworks/base/core/tests/coretests/src/android/os/FileUtilsTest.java
Bug: 28327846
Change-Id: I573aea43790816291e2b5c784b344b51b4444c06