Cache resource ID lookups in aapt

This speeds up certain workloads considerably, particularly
those involved in buildling apps via the SDK.  Windows-based
use should particularly benefit from the change.

Change-Id: I29f4b3a77400b201ee219729cc28a5e359c0c5e8
resolver list is not cleared on rebuild

Refactoring ResolverActivity.java

Change-Id: I84e6420ff98ddcafd27a52b041ddb1c50e7d7362
Signed-off-by: You Kim <you.kim72@gmail.com>