ASP.NET Core support

[j0nimost]

I have realized that the .Net pesaPi utilizes ASP.NET web form which is a really old version of web development. With the new robust .Net Core its only right that pesapal supports this new modern Framework.

[frmokoena]

that would be great. but I don't think the repo is being maintained as of now. There hasn't been any communication, pr review, etc since 2015.