[Modify][create_trip] remove unused services, add validation where necessary, and minor changes
[Add][auth-service.js] module for checking if user authenticated
[Delete][authen_token.js] unused
[Add][proxy.js] require http-proxy to act as the only one domain
Minor changes
[Modify][login.js ]re-design login services
[Add][follow.js] mongoose schema for follows collection
[Add][bookmark.js] mongoose schema for bookmarks collection
[Add][follow_user.js] services for 'follow'
[Add][bookmark_trip.js] services for 'bookmark'
[Modify][search_trip.js] implement GET /trip with checking if trip is bookmarked and if author is being followed