Replaced underscore and underscore.string modules with lodash

src/node/cli/service_packager.js

src/node/examples/perf_test.js

src/node/examples/route_guide_client.js

src/node/examples/route_guide_server.js

src/node/examples/stock_server.js

src/node/index.js

src/node/interop/interop_client.js

src/node/interop/interop_server.js

src/node/package.json

src/node/src/client.js

src/node/src/common.js

src/node/src/server.js

src/node/test/surface_test.js