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
how about having an `emulatorStartTimeout` option in the configuration, which would be passed to the service?
I'm not sure if we should add that to the command-line as an argument, but a configuration option might suffice.