Fix starting of emulator when a physical device is connected as well

Revert to old code for checking whether the emulator is started

refs https://github.com/NativeScript/nativescript-cli/issues/116 https://github.com/NativeScript/nativescript-cli/issues/114
On a virtual machine, starting an emulator takes "an eternity" (more than 5 minutes). I am not sure what is the correct UX in this case. Should I wait until 10 minutes pass? I am pretty sure that on non-virtual machines people would Ctrl-C long before the 10 minutes mark, while on virtual machines it may not be enough and we would needlessly time-out. 
I need your ideas how to do this right.