Look for correct metric ID to show CPU limit donut

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1396955

Author: spadgett

app/scripts/directives/podMetrics.js

@@ -213,7 +213,7 @@ angular.module('openshiftConsole')
               return ConversionService.bytesToMiB(usageValueFilter(memLimit));
             }
             break;
-          case 'cpu/usage':
+          case 'cpu/usage_rate':
             var cpuLimit = getCPULimit(container);
             if (cpuLimit) {
               // Convert cores to millicores.

dist/scripts/scripts.js

@@ -10476,7 +10476,7 @@ var c = w(b);
 if (c) return g.bytesToMiB(i(c));
 break;
 
-case "cpu/usage":
+case "cpu/usage_rate":
 var d = x(b);
 if (d) return _.round(1e3 * i(d));
 }