Hack! After failed test, node throws error which is pretty verbose in

console. To avoid that, we can force npm's script to return status 0.

We want to keep compatibility between Windows and Unix-like shells. As
Windows's cmd.exe doesn't implement such thing as `true` or `false`, I
had to get a bit creative - both shells implements `echo` command which
does what I need.

:+1:

package.json

@@ -7,7 +7,7 @@
     "compile": "babel exercises --out-dir src",
     "setup": "npm install && ncp koans/ exercises/",
     "start": "npm run compile && nodemon server.js",
-    "test": "npm run compile && mocha -b --compilers js:babel/register --require test/helpers.js test/**/*.js",
+    "test": "npm run compile && mocha -b --compilers js:babel/register --require test/helpers.js test/**/*.js || echo",
     "watch": "onchange exercises/*.jsx -- npm run test"
   },
   "repository": {