fmbtandroid: topApp/topWindow return None w/o connection
fmbtandroid: topApp/topWindow return None w/o connection

"adb devices" refactored to listSerialNumbers function.

rseymour/fMBT,giantpinkwalrus/fMBT,pombreda/fMBT,01org/fMBT,pombreda/fMBT,acozzette/fMBT,yoonkiss/fMBT,yoonkiss/fMBT,heivi/fMBT,rseymour/fMBT,acozzette/fMBT,rseymour/fMBT,rseymour/fMBT,mlq/fMBT,acozzette/fMBT,violep01/fMBT,mixu-/fMBT,acozzette/fMBT,pombreda/fMBT,pombreda/fMBT,mixu-/fMBT,rseymour/fMBT,pombreda/fMBT,yoonkiss/fMBT,mlq/fMBT,violep01/fMBT,mlq/fMBT,giantpinkwalrus/fMBT,heivi/fMBT,rseymour/fMBT,mixu-/fMBT,mixu-/fMBT,yoonkiss/fMBT,violep01/fMBT,heivi/fMBT,violep01/fMBT,pombreda/fMBT,acozzette/fMBT,rseymour/fMBT,pombreda/fMBT,heivi/fMBT,yoonkiss/fMBT,mlq/fMBT,mlq/fMBT,giantpinkwalrus/fMBT,mixu-/fMBT,mlq/fMBT,01org/fMBT,01org/fMBT,01org/fMBT,giantpinkwalrus/fMBT,giantpinkwalrus/fMBT,heivi/fMBT,violep01/fMBT,heivi/fMBT,heivi/fMBT,mlq/fMBT,01org/fMBT