Fix android emulator when more than one device is used

Remove adb wait-for-device call as it raises error when there's more than one device and/or emulator currently running. Use adb -s <emulatorId> instead of adb -e, so having more than one device currently running will not raise errors. Add printing of "Waiting for initialization......" when logging level is info and adding "." for each retry cycle. Add --retryCount option, so you can define the exact number of retries that will be executed before the emulate operation fails.

Fixes: 
http://teampulse.telerik.com/view#item/277469
https://github.com/NativeScript/nativescript-cli/issues/116
Well, I can remove the parameter and check for options.avd in startSimulatorCore, but do you think this will be fine? startEmulator is checking for image inside Mobile.IEmulatorOptions not for options.avd, so this will look very strange. Also you can create your own Mobile.IEmulatorOptions instance and pass specific image (in our code) and if I check for options.avd, I will not understand that you are using your own image passed as part of IEmulatorOptions. I'm open to any ideas for better approach in this case.