Create theme dir if needed (#49)

- Use Path.Combine throughout
- Update theme versions
- Update generator version

src/MyWebLog/appsettings.json

@@ -1,5 +1,5 @@
 {
-  "Generator": "myWebLog 2.1.1",
+  "Generator": "myWebLog 2.2",
   "Logging": {
     "LogLevel": {
       "MyWebLog.Handlers": "Information"