Added MACHINE_FEATURES and IMAGE_FSTYPES variables to the build config
to ensure that bootimg and efi artifacts are built. This is needed to
build canned wic images that are using those artifacts.
Introduced class variable Wic.image_is_ready to avoid building image
more than once. It would be better to build image in setUpClass, which
is called only once, but add_config method can't be called in class method,
so we have to use this trick with class variable in setUp method.
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
