fix(package): update semver to version 6.0.0

Closes #85

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
     "nedb-promise": "^2.0.1",
     "request": "^2.88.0",
     "request-promise-native": "^1.0.5",
-    "semver": "^5.5.1",
+    "semver": "^6.0.0",
     "socket.io": "^2.1.1",
     "universal-analytics": "^0.4.17",
     "winston": "^3.1.0",