Create theme dir if needed (#49)

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

src/MyWebLog.Tests/Domain/ViewModelsTests.fs

@@ -118,16 +118,19 @@ let displayThemeTests = testList "DisplayTheme.FromTheme" [
         Expect.isFalse model.IsOnDisk "IsOnDisk should not have been set"
     }
     test "succeeds when a non-default theme is not in use and is on disk" {
-        let dir  = Directory.CreateDirectory "themes"
-        let file = File.Create "./themes/another-theme.zip"
+        let dir = Directory.CreateDirectory "themes"
         try
-            let model = DisplayTheme.FromTheme (fun _ -> false) { theme with Id = ThemeId "another" }
-            Expect.isFalse model.IsInUse "IsInUse should not have been set"
-            Expect.isTrue model.IsOnDisk "IsOnDisk should have been set"
+            let testFile = Path.Combine(".", "themes", "another-theme.zip")
+            let file     = File.Create testFile
+            try
+                let model = DisplayTheme.FromTheme (fun _ -> false) { theme with Id = ThemeId "another" }
+                Expect.isFalse model.IsInUse "IsInUse should not have been set"
+                Expect.isTrue model.IsOnDisk "IsOnDisk should have been set"
+            finally
+                file.Close()
+                file.Dispose()
+                File.Delete testFile
         finally
-           file.Close()
-           file.Dispose()
-           File.Delete "./themes/another-theme.zip"
            dir.Delete()
     }
     test "succeeds when the default theme is on disk" {