Fix issue with updating when targeting Nougat or higher

[LanceJenkinZA]

This pull request mainly fixes an issue when targeting Nougat.

The authorities section in of the provider tag in plugin.xml was set to "com.vaenow.appupdate.android.provider.${applicationId}". However, in DownloadHandler.java, the plugin was calling com.vaenow.appupdate.android.provider.

I changed plugin.xml.

I also updated the Javascript function to be called without success or error callback functions (to be compatible with ionic-native).

[vaenow]

42 #21

[vaenow]

Awsome @LanceJenkinZA 🙂