Update base element to make use of pkg-map

With this change package name to distro mappings used
within the base element are now stored in the top
level pkg-map file.

Additionally, all bin/install-packages commands are updated
to use the -m option so that the base element pkg-map
namespace is used by default.

Change-Id: I3bdbf987c8525f9ef67ca0c263651d6613f29ef0

elements/base/element-deps

@@ -0,0 +1 @@
+pkg-map

elements/base/install.d/00-baseline-environment

@@ -4,4 +4,4 @@
 set -eu
 set -o pipefail
 
-install-packages vlan open-iscsi
+install-packages -m base vlan_package iscsi_package

elements/base/install.d/00-ccache

@@ -3,4 +3,4 @@
 set -eu
 set -o pipefail
 
-install-packages ccache
+install-packages -m base ccache_package

elements/base/install.d/99-dkms

@@ -3,4 +3,4 @@
 set -eu
 set -o pipefail
 
-install-packages dkms
+install-packages -m base dkms_package

elements/base/pkg-map

@@ -0,0 +1,14 @@
+{
+  "family": {
+    "redhat": {
+      "vlan_package": "vconfig",
+      "iscsi_package": "iscsi-initiator-utils"
+    }
+  },
+  "default": {
+    "ccache_package": "ccache",
+    "dkms_package": "dkms",
+    "vlan_package": "vlan",
+    "iscsi_package": "open-iscsi"
+  }
+}