Update lodash version to ^4.17.5 (#330)

This should resolve warnings related to
https://nodesecurity.io/advisories/577

packages/grpc-health-check/package.json

@@ -17,7 +17,7 @@
   "dependencies": {
     "google-protobuf": "^3.4.0",
     "grpc": "^1.6.0",
-    "lodash": "^3.10.1"
+    "lodash": "^4.17.5"
   },
   "files": [
     "LICENSE",

packages/grpc-js-core/package.json

@@ -14,7 +14,7 @@
   "types": "build/src/index.d.ts",
   "license": "Apache-2.0",
   "devDependencies": {
-    "@types/lodash": "^4.14.77",
+    "@types/lodash": "^4.14.108",
     "@types/mocha": "^2.2.43",
     "@types/node": "^9.4.6",
     "clang-format": "^1.0.55",

packages/grpc-native-core/package.json

@@ -28,7 +28,7 @@
     "node-pre-gyp"
   ],
   "dependencies": {
-    "lodash": "^4.15.0",
+    "lodash": "^4.17.5",
     "nan": "^2.0.0",
     "node-pre-gyp": "^0.10.0",
     "protobufjs": "^5.0.0"