contextual notes pollute browser history

[rlskoeser]

If you're reading through an article and read the notes as you go, then you want to use the browser back button to go back to the issue list to read a different article, you have to go back through every note you read because they are in the browser history as distinct urls.

The contextual note js should be updated so that it changes the location (so you can still link to a specific note) but doesn't pollute the browser history — maybe when the note is closed.

[rlskoeser]

merged into develop in #278