samples: add a collection of samples

These are meant to test the various assembers and stages and to show how pipelines
can be created. However, they are not meant to necessarily be the best way to create
any given image.

Note that some of the pipelines are dependent on each other.

samples/base.json

@@ -0,0 +1,29 @@
+{
+  "name": "base",
+  "stages": [
+    {
+      "name": "io.weldr.dnf",
+      "systemResourcesFromEtc": ["/etc/pki"],
+      "options": {
+        "releasever": "29",
+        "repos": {
+          "fedora": {
+            "name": "Fedora",
+            "metalink": "https://mirrors.fedoraproject.org/metalink?repo=fedora-$releasever&arch=$basearch",
+            "gpgkey": "file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$releasever-$basearch"
+          }
+        },
+        "packages": [
+          "@Core"
+        ]
+      }
+    }
+  ],
+  "assembler":
+    {
+      "name": "io.weldr.tree",
+      "options": {
+        "tree": "base"
+      }
+    }
+}