MDL-42668 portfolio_boxnet: Migration to APIv2

Conflicts:

	lib/boxlib.php
MDL-42668 portfolio_boxnet: Notify the admins about the upgrade process

Conflicts:

	portfolio/boxnet/version.php
MDL-42668 portfolio_boxnet: Disable the portfolio during upgrade
MDL-42668 portfolio_boxnet: Disable the portfolio when non-HTTPS