fix(): updated changelog

CHANGELOG.md

-# 3.0.0-beta7 (unreleased)
+# 3.0.0-beta7 (2016-05-02)
 
 
 ### Bug fixes
 ### Bug fixes
 * **Dashboard title**: Fixed max dashboard title width (media query) for large screens,  fixes [#4859](https://github.com/grafana/grafana/issues/4859)
 * **Dashboard title**: Fixed max dashboard title width (media query) for large screens,  fixes [#4859](https://github.com/grafana/grafana/issues/4859)

latest.json

 {
 {
   "stable": "2.6.0",
   "stable": "2.6.0",
-	"testing": "3.0.0-beta5"
+	"testing": "3.0.0-beta7"
 }
 }