By default, the `rendererBackground` code will choose an initial imagery based on what
sources are available at the given map location. It looks like this code will fallback
to "custom" _before_ "none", and I noticed that in some cases it was trying to fetch
whatever source happened to be stored in the "custom" template in localStorage.
This commit adds an explicit window.location.hash in a few places to encourage the
background layer to be "none". Some tests do change the hash, so this isn't perfect.
Also stringify the note id (because existing notes from OSM are this way)
Also make sure comments is initialized as an Array not an Object
Also clarify some of the tests
