meta-nicole: Add image signature verification

Adds a firmware image signature verification.

This brings:
 - The key is stored in `/etc/activationdata` folder.
 - The software item activation now begins with signature verification.
   The verification failure stops the activation only when the
   `fieldMode` is set to true.
   See https://github.com/openbmc/phosphor-dbus-interfaces/blob/master/xyz/openbmc_project/Control/FieldMode.interface.yaml

Change-Id: I158f7430117da097de90899e1a677880c94b37ce
Signed-off-by: Alexander Filippov <a.filippov@yadro.com>
diff --git a/meta-nicole/recipes-phosphor/packagegroups/packagegroup-obmc-apps.bbappend b/meta-nicole/recipes-phosphor/packagegroups/packagegroup-obmc-apps.bbappend
index 31e4f5b..26e64be 100644
--- a/meta-nicole/recipes-phosphor/packagegroups/packagegroup-obmc-apps.bbappend
+++ b/meta-nicole/recipes-phosphor/packagegroups/packagegroup-obmc-apps.bbappend
@@ -2,6 +2,9 @@
 RDEPENDS_${PN}-extras_append = " \
     phosphor-hostlogger \
     openpower-esel-parser \
-    obmc-yadro-fwupdate \
     obmc-yadro-lssensors \
 "
+RDEPENDS_${PN}-software_append = " \
+    obmc-yadro-fwupdate \
+    phosphor-image-signing \
+"