use etag instead of last-modified.  Last-modified dates for AIR SDKs becaome unstable.  Sometimes it would give you different dates for the same file
Revert "use etag instead of last-modified.  Last-modified dates for AIR SDKs becaome unstable.  Sometimes it would give you different dates for the same file"

This reverts commit 301f030eaa2f5b789cd4574baf2d294f95a749fd.
flexicious