user authentication

[aninda052]

This pr will close #35

server

• user login and registration api added
• hash password before storing in db using bcrypt package
• add JWT based authentication system using jsonwebtoken package
• setCurrentUser middleware is used for binding current user with request
• loginRequired middleware will used for protected route
• made /api/videos/update, /api/videos/delete and /api/videos/upload as protected route
• store jwt token in cookies with httpOnly=true

client

• integrate login and registration api
• implement protected route
• showing alert using global context & state
• redirect anonymous user to login page and navigate them to their desire page after successful login.
• after successful login, store user info in local storage