NS7 Support

[agonper]

This PR adds support for NS7 for this plugin. Given NS7 is not backwards compatible with NS6, it also includes the proposal to bump plugin version to v2.

This PR includes:

• Migration of the plugin config files to NS7.
• Migration of plugin sources to NS7.
• Migration of plugin demo to NS7.
• Ensures tests are still operational (they have been updated to make use of @nativescript/core too).
• Simplifies the plugin packaging process by removing the scripts folder.

Fixes #18 and probably adds support for NS8 too (not tested yet)

[agonper]

Thanks to you @matey97 for reviewing this so fast!