Refactored and updated plugin to work with update API and to be able to
be packaged and distributed using more than just GitHub

Added a script to delete old extension, installing the new extension overrides the previous extension and the previous extensions does not function anymore, merchants should at least disable the previous plugin, the merchant will also need to also remove the extension from core_resource table

Updated to encrypt/decrypt keys to and from the database

Small bug fixes with the package script

Added instructions on how a previous merchant can upgrade to the new 2.x one