[Test] Use PhantomJS to run tests

Switch Karma to use PhantomJS to run tests.  CI machines no longer
need to have Chrome installed.

Implemented after changes to build process due to imperative registration.

https://github.com/nasa/openmctweb/issues/450

test-main.js

@@ -51,5 +51,13 @@ require.config({
     deps: allTestFiles,
 
     // we have to kickoff jasmine, as it is asynchronous
-    callback: window.__karma__.start
+    callback: function () {
+        var args = [].slice.apply(arguments);
+        require(['es6-promise'], function (es6Promise) {
+            if (!window.Promise) {
+                window.Promise = es6Promise.Promise;
+            }
+            window.__karma__.start.apply(window.__karma__, args);
+        });
+    }
 });