Improve message for unable to emulate

Improve message when android emulator cannot start. When the virtual device is using Android L and its RAM <= 512MB the emulator cannot start the application. Moved sleeping at the end of each retry when checking for emulator boot in order to prevent unnecessary 10 secs wait.
Merge pull request #81 from telerik/vladimirov/fix-android-L

Improve message for unable to emulate