start some deps for promoting the standbay server to master
remove duplication from failover deps
use a TTL of 60 seconds when changing key DNS entries
add babushka deps for doing a staging failover
failover deps can now promote psql from standby to master

* use with caution!
double check the user is ready to failover

* there's no going back once this starts!
Merge branch 'failover-script'