v1.4.0-docs1

• Release date: 2017-06-28. Live on prod 2017-06-??.
• Requires: tileserver v2.1.0 and tilequeue v1.9.0 and mapbox-vector-tile v1.2.0.

• [docs] Update link to pois.jinja2. See #1268.
• [docs] Update your-mapzen-api-key URL query strings to enable key substitution. See #1275.
• [docs] Spelling, grammar, writing style fixes. See #1275.
• [docs] Add documentation for 512 pixel tile sizes. See #1284.
• [docs] Add documentation to suggest max zoom (per tile size). See #1161.
• [docs] Add documentation for tile x, y coordinates (versus latitude and longitude). See #1111.
• [docs] Add documentation for HTTP status codes. See #1266.
• [tests] Update tests for upstream OpenStreetMap data churn. See #1267, #1282, and #1286.
• Remove duplicate symbol output. See #1265.
• Fixed release notes on 2017-07-19 and 2017-07-25 with corrected Requires section.