updated package dependency to yarn

[dhuang612]

used bower-away npm package and yarn to move away from bower. generated a yarn.lock file updated node version that the application accepted up to node v8.16.0 ran yarn start and confirmed I could bring up development server.

TallyCTF - Development Environment
Environment:            development
Port:               3000
Database:               mongodb://localhost/mean-dev
App version:            0.4.2
MEAN.JS version:            0.4.2

Please let me know if there is anything else that needs to be changed

[securityvoid]

Thank-you @dhuang612 !