Add Firebase rules to Proguard configuration
Add Firebase rules to Proguard configuration

Fix for crash on startup observed by some users.

Change-Id: Ie6ddc0a1040314d80e14a11bf1aed0bb32d8e3a1

google/iosched,WeRockStar/iosched,amardeshbd/iosched,amardeshbd/iosched,jarekankowski/iosched,amardeshbd/iosched,google/iosched,google/iosched,epiphany27/iosched,WeRockStar/iosched,epiphany27/iosched,epiphany27/iosched,jarekankowski/iosched,amardeshbd/iosched,jarekankowski/iosched,WeRockStar/iosched