chore(package): update semantic-release to version 15.1.4

Closes #31

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
     "express": "^4.13.4",
     "istanbul": "0.4.5",
     "mocha": "^4.0.0",
-    "semantic-release": "11.0.2",
+    "semantic-release": "15.1.4",
     "should": "^13.1.0",
     "sqlite3": "^3.1.1",
     "supertest": "2.0.1",