bump to 0.5 in master

router/middleware/version.go

@@ -0,0 +1,12 @@
+package middleware
+
+import (
+	"github.com/drone/drone/version"
+	"github.com/gin-gonic/gin"
+)
+
+// Version is a middleware function that appends the Drone version information
+// to the HTTP response. This is intended for debugging and troubleshooting.
+func Version(c *gin.Context) {
+	c.Header("X-DRONE-VERSION", version.Version)
+}