[soundwave] Make fetch_alerts_data interpret days as an int.
[soundwave] Make fetch_alerts_data interpret days as an int.

IT currently passes it as a string, which causes problems later when
it is assumed to be an int.

Bug: chromium:769027
Change-Id: I12e5b5ede7e4cca2e7d49fca9fcfd9d61f268667
Reviewed-on: https://chromium-review.googlesource.com/763568
Commit-Queue: Charlie Andrews <532d7316e2689bea110898693dc3dc5671811b69@chromium.org>
Reviewed-by: Charlie Andrews <532d7316e2689bea110898693dc3dc5671811b69@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult