Remove 'dey-test' image feature and create a SARES bbclass with the
same functionality. This makes easier the creation of images suitable
for SARES testing just adding:
INHERIT += "sares-image"
to your project's local.conf
https://jira.digi.com/browse/DEL-1558
Signed-off-by: Javier Viguera <javier.viguera@digi.com>