fix: Drop karma from peerDependencies

This avoids a lot of issues we are having with peerDependencies.

BREAKING CHANGE:

Karma is no longer a `peerDependency` so it needs to be installed
manually.

Ref karma-runner/integration-tests#5

package.json

@@ -23,9 +23,6 @@
     "dateformat": "^1.0.6",
     "minimatch": "^2.0.8"
   },
-  "peerDependencies": {
-    "karma": ">=0.9"
-  },
   "license": "MIT",
   "devDependencies": {
     "chai": "^2.3.0",