Add Button to update iD Editor Presets

[tordans]

It would be great to have button in the app, that pulls the latest presets for tags from the iD Editor Repository. (Same idea as with #118.)

ATM the presets seem to be included in the app which is release only every other year.

So even if #111 is solved and the new app is released, the next change might tage a long while before it is included.

This button could update

• The list of presents
• The specs for which elements have an icon on the map

[bryceco]

Unfortunately it isn't possible to automatically download new presets dynamically because iD will occasionally change things that require code changes as well, so the new presets could cause crashes or other weirdness.