Set Chart.js animation duration

Animate lines after loading

https://github.com/CachetHQ/Cachet/pull/1625#issuecomment-197856024

resources/views/partials/metrics.blade.php

@@ -36,6 +36,7 @@
 <script>
 (function () {
     Chart.defaults.global.elements.point.hitRadius = 10;
+    Chart.defaults.global.responsiveAnimationDuration = 1000;
     Chart.defaults.global.legend.display = false;
 
     var charts = {};