Hardcoding karma version number to 0.13.15 until a gulp-related bug i…

…s solved.

See:
- karma-runner/karma#1788
- karma-runner/karma#1782

package.json

@@ -42,7 +42,8 @@
     "jasmine-terminal-reporter": "^1.0.0",
     "jscs": "^2.4.0",
     "jshint": "^2.7.0",
-    "karma": "^0.13.3",
+    "//": "Fixing karma version number to 0.13.15 because https://github.com/karma-runner/karma/issues/1788",
+    "karma": "=0.13.15",
     "karma-chrome-launcher": "^0.2.0",
     "karma-firefox-launcher": "^0.1.6",
     "karma-jasmine": "^0.3.6",
@@ -82,6 +83,7 @@
     "run-sequence": "^1.1.2",
     "selenium-standalone": "^4.6.0",
     "semver": "^5.1.0",
+    "socket.io": "1.3.7",
     "stream-combiner": "^0.2.2",
     "stylelint": "^1.1.0",
     "stylelint-statement-max-nesting-depth": "^0.4.0",