added nvmrc with usage of stable Node.js version
added nvmrc with usage of stable Node.js version

gAmUssA/hazelcast-nodejs-client,gAmUssA/hazelcast-nodejs-client,hazelcast-incubator/hazelcast-nodejs-client,gAmUssA/hazelcast-nodejs-client,gAmUssA/hazelcast-nodejs-client,hazelcast-incubator/hazelcast-nodejs-client