Creating an LXD VM host now requires a project name

[Lee Trager]

In previous versions of MAAS adding a VM host did not require a project. As of 3.0 when you add an LXD VM host you must provide a project name. This causes API incompatibilities for existing users. When no project is given the "default" project should be used as to not break existing users.

maas $PROFILE vmhosts create type=lxd power_address=$LXD_HOST_IP power_pass=$PASSWORD
{"project": ["This field is required."]}