Remove appstats (a Python 3 migration blocker) (#1372)
Remove appstats (a Python 3 migration blocker) (#1372)

Not compatible with Python 3.7 GAE standard environment, and can mostly be achieved with stackdriver traces anyway.
gae-init/gae-init,mdxs/gae-init,mdxs/gae-init,gae-init/gae-init,mdxs/gae-init,gae-init/gae-init,mdxs/gae-init,gae-init/gae-init