Add virtual workbook / config-in-skeleton classes

This patch introduces a new abstraction 'skeleton-workbook'
for representing a system configuration.  At present it is
pulled in by the skeleton recipe so the requirement on what is
implemented by a package providing obmc-phosphor-workbook is something
compatible with the existing System.py python modules in skeleton.

Additionally this patch adds a new recipe for each system using
a configuration file from skeleton today, and a class for common
configuration.

This enables a couple of things:
 - No need to patch skeleton.service for each system.
 - New systems don't have to put their configuration in the skeleton
     repository.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-openbmc-machines/meta-openpower/conf/machine/include/openpower.inc b/meta-openbmc-machines/meta-openpower/conf/machine/include/openpower.inc
index 6660a56..2ef42ed 100644
--- a/meta-openbmc-machines/meta-openpower/conf/machine/include/openpower.inc
+++ b/meta-openbmc-machines/meta-openpower/conf/machine/include/openpower.inc
@@ -23,6 +23,8 @@
         host-ipmid-oem \
         host-ipmid-fru \
        "
+VIRTUAL-RUNTIME_skeleton_workbook = "${MACHINE}-config"
+
 PREFERRED_PROVIDER_virtual/obmc-phosphor-host-ipmi-hw = "btbridged"
 PREFERRED_PROVIDER_virtual/obmc-phosphor-chassis-mgmt = "skeleton"
 PREFERRED_PROVIDER_virtual/obmc-phosphor-event-mgmt = "obmc-phosphor-event"