Formatting changes to conform to the new Elm style guide.

The Elm style guide is a work in progress:
https://gist.github.com/laszlopandy/c3bf56b6f87f71303c9f

I am using this repository to test how it looks on real code.
@evancz 
It's not obvious to me if the `[` should go on a new line or not. I definitely want it on the same line if it is after an equals sign (ie. `let signals = [`), and if there are multiple parameters to the function each should have its own line.

But here, with only one parameter it isn't clear either way. @evancz