Follow installd changes, throw exceptions.

Start by passing down flags to work on both CE and DE storage areas;
a future change will refine this further.

Force consistent argument checking and null handling for all
installd callers.  Throw explicit exceptions instead of returning int
values that can accidentally be ignored.

Bug: 26466827
Change-Id: Iddb591f6b3c7786d210d3f132ff7f9886a97b749