Add snowpack as an example project. (#11)

* Initial tests set up

This adds tests using uvu (we can switch if people want) and restructures things a bit so that it's easier to test.

Like in snowpack you set up a little project. In our tests you can say:

```js
const result = await runtime.load('/blog/hello-world')
```

And analyze the result. I included a `test-helpers.js` which has a function that will turn HTML into a cheerio instance, for inspecting the result HTML.

* Bring snowpack example in

* Formatting

1 files changed, 4 insertions, 0 deletions

diff --git a/examples/snowpack/.prettierrc b/examples/snowpack/.prettierrc
new file mode 100644
index 000000000..a20502b7f
--- /dev/null
+++ b/examples/snowpack/.prettierrc
@@ -0,0 +1,4 @@
+{
+  "singleQuote": true,
+  "trailingComma": "all"
+}