update changelog for 1.27.0

Author: etpinard

CHANGELOG.md

@@ -10,6 +10,37 @@ https://github.com/plotly/plotly.js/compare/vX.Y.Z...master
 where X.Y.Z is the semver of most recent plotly.js release.
 
 
+## [1.27.0] -- 2017-05-10
+
+### Added
+- Sankey diagram with new trace type `sankey` [#1591, #1664]
+- Add `hoverlabel` trace and layout attributes to customize hover label colors
+  and fonts [#1582]
+- Add `marker.gradient` attributes for `scatter`, `scattergeo`, `scatterternary`
+  and `scattercarpet` traces [#1620]
+- Add `sort` transform [#1609]
+- Add `preservegaps` `filter` transform attribute [#1589]
+- Add `!=` (not equal) `filter` transform operation [#1589]
+- Add `labelfont`, `tickfont` and `rangefont` attributes for `parcoords` traces
+  [#1624]
+- Pass DOM mouse event on `plotly_clickannotations` events [#1652]
+
+### Changed
+- Performance optimization for range sliders and Drawing cache [#1585]
+
+### Fixed
+- Fix `scattergl` marker symbol positioning (bug introduced in 1.25.0) [#1633]
+- Fix gl2d zoom where two clicks would trigger a zoom box (bug introduced 1.26.0) [#1632]
+- Fix legend double click handler for `carpet` traces [#1636]
+- Fix `restyle` for `scattercarpet` for style attributes with array support [#1641]
+- Fix `restyle` for array layout components when more than 10 items are present
+  [#1639]
+- Fix select-box and lasso selections so that they don't include bad-data items
+  [#1656]
+- Fix `restyle` for contour `zmin` and `zmax` [#1653]
+- Fix `scatter` text node transitions [#1616, #1626]
+
+
 ## [1.26.1] -- 2017-04-21
 
 ### Fixed