Fixing various project-helper scripts

fixes:
* CB-2979 Add a ./cordova/lib/list-devices project-level helper script to OSX
* CB-2971 Add a ./cordova/lib/list-started-emulators as project-level helper script to OSX
* CB-2954 Add a ./cordova/lib/list-emulator-images project-level helper script to OSX
* CB-2987 Add a ./cordova/lib/install-emulator project-level helper script to OSX
* CB-2995 Add a ./cordova/lib/install-device project-level helper script to OSX
* CB-3003 Add a ./cordova/lib/start-emulator project-level helper script to OSX