Update mocha to 6.0.2

package.json

@@ -43,7 +43,7 @@
     "jayson": "^1.2.2",
     "json-loader": "^0.5.2",
     "json-schema-to-markdown-table": "^0.4.0",
-    "mocha": "^2.1.0",
+    "mocha": "6.0.2",
     "mocha-in-sauce": "^0.0.1",
     "mocha-junit-reporter": "^1.9.1",
     "null-loader": "^0.1.1",
@@ -66,7 +66,7 @@
     "compile": "mkdir -p dist/npm/common && cp -r src/common/schemas dist/npm/common/ && tsc",
     "watch": "tsc -w",
     "prepublish": "npm run clean && npm run compile && npm run build",
-    "test": "nyc mocha",
+    "test": "nyc mocha --exit",
     "coveralls": "cat ./coverage/lcov.info | coveralls",
     "lint": "tslint -p ./",
     "perf": "./scripts/perf_test.sh",