Add newline for empty blocks {} (#205)

I find it weird to put `{}` together. So I figured I would change it to have an empty line and ask for feedback :)

![image](https://cloud.githubusercontent.com/assets/197597/21739279/062adc80-d44c-11e6-8bb7-5e0768f3ddde.png)

Beware: most of the test cases are not representative of real code, you almost never define blocks with no content in practice.

tests/singleton/__snapshots__/jsfmt.spec.js.snap

@@ -122,7 +122,8 @@ bar(2);
 bar(3);
 // error
 type ComparatorResult = -1 | 0 | 1;
-function sort(fn: (x: any, y: any) => ComparatorResult) {}
+function sort(fn: (x: any, y: any) => ComparatorResult) {
+}
 sort((x, y) => -1);
 "
 `;