puppetboard/app.py: Adding Radiator view (#232)

* puppetboard/app.py: Adding Radiator view

Part 2 of https://github.com/voxpupuli/puppetboard/issues/70

This is a refactoring of the changes in https://github.com/voxpupuli/puppetboard/pull/100.
Adds a simple Heads-Up Display of the last run statuses of managed nodes,
either environment filtered or not.

* puppetboard/app.py: Fixing environment filters and metric strings.

* The names of the population metrics have changes in PuppetDB 4.0, the initial
  commit used the metric names from PuppetDB 2.x.
* The main nodes query did not include a query string to filter on environments.

puppetboard/static/js/radiator.js

@@ -0,0 +1,21 @@
+function resizeMe() {
+  var preferredHeight = 944;
+  var displayHeight = $(window).height();
+  var percentageHeight = displayHeight / preferredHeight;
+
+  var preferredWidth = 1100;
+  var displayWidth = $(window).width();
+  var percentageWidth = displayWidth / preferredWidth;
+
+  var newFontSize;
+  if (percentageHeight < percentageWidth) {
+    newFontSize = Math.floor("960" * percentageHeight) - 30;
+  } else {
+    newFontSize = Math.floor("960" * percentageWidth) - 30;
+  }
+  $("body").css("font-size", newFontSize + "%")
+}
+
+$(document).ready(function() {
+    $(window).on('resize', resizeMe).trigger('resize');
+})