Update mocha to the latest version 🚀 (#60)

* chore(package): update mocha to version 4.0.0

* Adding --exit flag

Author: greenkeeper[bot]

mocha.opts

@@ -1,2 +1,3 @@
 --recursive test/
---compilers js:babel-core/register
+--compilers js:babel-core/register
+--exit

package.json

@@ -77,7 +77,7 @@
     "feathers-memory": "^1.0.0",
     "istanbul": "^1.1.0-alpha.1",
     "lodash": "^4.0.1",
-    "mocha": "^3.0.0",
+    "mocha": "^4.0.0",
     "rimraf": "^2.5.4",
     "semistandard": "^11.0.0",
     "uws": "^8.14.0",