Minor documentation improvements.

Fix unqualified uses of SimpleDateFormat in TimeZone.java, explain how to use
getPercentageInstance (http://code.google.com/p/android/issues/detail?id=10333),
add an explicit test to make sure no-one accidentally "fixes" that
odd-but-correct behavior, and remove an example from the DecimalFormat
documentation that doesn't really clarify anything.

Bug: http://code.google.com/p/android/issues/detail?id=10333
Change-Id: I52f22d817c7c6c32ad38fb6953fbe909a76f8943
4 files changed