Fix the productName value when attributes are used

[david-spaeth]

Fix the bad value of productName variable if short attribute has use in name tag
Cordova allow short attribute in name tag. See: https://cordova.apache.org/docs/en/latest/config_ref/#short-name

[ivar-tp]

Was about to create the same pull request. Merging this is much appreciated since using short attribute is a common scenario and at this point returns an object. Also the workaround as suggested here #125 does not work ok in all scenario's since it messes the App's name in some cases.

Also the fix done for android old paths is a good one that prevents manual copying for older setups using latest version of the cordova-icon plugin