Initial implementation of some karma/mocha tests

It does something, but things I don't like:

* it churns for 15 seconds webpacking everything. Do we really need to get
  webpack involved here?

* I don't think there's any way to control which tests get run and which don't.

Other things I'd want to fix up include:

* Make it run on jsdom or phantomjs instead of Chrome
* figure out how to configure babel without a .babelrc

package.json

@@ -17,7 +17,9 @@
     "build": "babel src -d lib --source-maps",
     "start": "babel src -w -d lib --source-maps",
     "clean": "rimraf lib",
-    "prepublish": "npm run build; git rev-parse HEAD > git-revision.txt"
+    "prepublish": "npm run build; git rev-parse HEAD > git-revision.txt",
+    "test": "karma start",
+    "test-multi": "karma start --single-run=false"
   },
   "dependencies": {
     "classnames": "^2.1.2",
@@ -45,6 +47,15 @@
     "json-loader": "^0.5.3",
     "require-json": "0.0.1",
     "rimraf": "^2.4.3",
-    "source-map-loader": "^0.1.5"
+    "source-map-loader": "^0.1.5",
+
+    "karma": "^0.0.0",
+    "karma-cli": "^0.0.0",
+    "karma-mocha": "^0.0.0",
+    "karma-webpack": "^0.0.0",
+    "karma-sourcemap-loader": "^0.0.0",
+    "karma-chrome-launcher": "^0.0.0",
+    "mocha": "^0.0.0",
+    "expect": "^0.0.0"
   }
 }