Add boilerplate version upgrade plug-in

This plug-in does nothing at the moment. It merely says that it is able to upgrade configuration from version 2.1 to 2.2, but then raises exceptions when you actually try to use it. This is by design. I will now implement the functions that do the conversion.

Contributes to issue CURA-844.

plugins/VersionUpgrade/VersionUpgrade21to22/__init__.py

@@ -0,0 +1,35 @@
+# Copyright (c) 2015 Ultimaker B.V.
+# Cura is released under the terms of the AGPLv3 or higher.
+
+from . import VersionUpgrade21to22
+
+from UM.i18n import i18nCatalog
+catalog = i18nCatalog("cura")
+
+def getMetaData():
+    return {
+        "plugin": {
+            "name": catalog.i18nc("@label", "Version Upgrade 2.1 to 2.2"),
+            "author": "Ultimaker",
+            "version": "1.0",
+            "description": catalog.i18nc("@info:whatsthis", "Upgrades configurations from Cura 2.1 to Cura 2.2."),
+            "api": 2
+        },
+        "version_upgrade": {
+            "profile": {
+                "from": 1,
+                "to": 2
+            },
+            "preferences": {
+                "from": 2,
+                "to": 3
+            },
+            "machine_instance": {
+                "from": 1,
+                "to": 2
+            }
+        }
+    }
+
+def register(app):
+    return { "version_upgrade": VersionUpgrade21to22.VersionUpgrade21to22() }