Update to iD v2.15.4

[quincylvania]

2.15.4

2019-Jul-26

🎉 New Features

• Render side direction arrows on weirs (#6615)

✨ Usability

• Don't reuse the changeset comment, sources, and hashtags by default after uploading or discarding edits (#6642)

✅ Validation

• Don't flag very close points on different layers or levels (#6612)
• Don't flag Google Books as a source (#6556)
• Add preschool=yes when upgrading amenity=preschool (#6636)

🐛 Bugfixes

• Fix issue where the info in the Background panel wouldn't update when switching backgrounds (#6627)
• Fix issue where side direction arrows might not update when switching presets (#6032)

🌏 Localization

• Default speed limit units to miles per hour in Puerto Rico (#6626)
• Fix issue where Arabic numerals would not render correctly on the map (#6679, #6682, thanks @mapmeld)

🚀 Presets

• Add Dressing Room preset (#6643)
• Add Pool Supply Store preset (#6599)
• Add Address Interpolation line preset (#4220)
• Add Printer Ink Store, Park & Ride Lot, Aircraft Holding Position, and Aircraft Parking Position presets
• Add Type and Address fields to Public Bookcase preset (#6564, thanks @ToastHawaii)
• Add Underground Levels field to building presets (#6628)
• Add more fields to the Kindergarten, Ferry Route, Ford, Dam, Weir, and Bridge Support presets
• Fix tag misspelling for the Camp Pitch preset (#6608)
• Update icons for the Cairn, Sandwich Fast Food, Hifi Store, and Party Store presets

[quincylvania]

I'm not sure what the config/application.yml file is. It seems to have tagged along in our release pipeline.

Update: I removed it from this PR.