Added karma tests for angular.js to travis.

Installed required dependencies to run karma test in phantomjs which
is a supported browser by travis.

.travis.yml

@@ -23,6 +23,7 @@ script:
   - flake8 openslides tests
   - isort --check-only --recursive openslides tests
   - node_modules/.bin/gulp jshint
+  - node_modules/.bin/karma start --browsers PhantomJS tests/karma/karma.conf.js
 
   - DJANGO_SETTINGS_MODULE='tests.settings' coverage run ./manage.py test tests.unit
   - coverage report --fail-under=44

package.json

@@ -23,8 +23,10 @@
     "jshint": "~2.9.2",
     "karma": "~1.1.0",
     "karma-chrome-launcher": "~1.0.1",
+    "karma-phantomjs-launcher": "~1.0.0",
     "karma-jasmine": "~1.0.2",
     "main-bower-files": "~2.11.1",
+    "phantomjs-prebuilt": "~2.1.14",
     "po2json": "~0.4.1",
     "sprintf-js": "~1.0.3",
     "through2": "~2.0.0",

tests/karma/karma.conf.js

@@ -63,12 +63,12 @@ module.exports = function(config) {
 
     // start these browsers
     // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
-    browsers: ['Chrome'],
+    browsers: ['Chrome', 'PhantomJS'],
 
 
     // Continuous Integration mode
     // if true, Karma captures browsers, runs the tests and exits
-    singleRun: false,
+    singleRun: true,
 
     // Concurrency level
     // how many browser should be started simultaneous