Make admin module runs on backend.
Move shard.py to lib (common code)
Add module cron to run scheduled jobs.

Currently, there is one job runs on midnight to calculate daily
device register count for every gcm app.
Increase device count when registering successfully.
Handle transactionFailedError exception.
Show recently 7 days device register count.
Need to pass unicode string to Jinja template.

Or pass byte string if there is only ascii in the string.
Set focusTarget to category.

See: https://developers.google.com/chart/interactive/docs/gallery/linechart?csw=1#Configuration_Options