adding exercise5

exercises/exercise5/Exercise5Description.md

...5/postmanSampleResponses/create-another-user-response.png

exercises/exercise5/postmanSampleResponses/create-tweet.png

...exercise5/postmanSampleResponses/create-user-response.png

.../exercise5/postmanSampleResponses/retrieve-all-tweets.png

...s/exercise5/postmanSampleResponses/retrieve-all-users.png

...exercise5/postmanSampleResponses/retrieve-single-user.png

exercises/exercise5/twitter-api/.gitignore

exercises/exercise5/twitter-api/app.js

exercises/exercise5/twitter-api/bin/www

exercises/exercise5/twitter-api/client.rest

...cises/exercise5/twitter-api/controllers/UserController.js

exercises/exercise5/twitter-api/index.js

exercises/exercise5/twitter-api/models/Tweet.js

exercises/exercise5/twitter-api/models/User.js

exercises/exercise5/twitter-api/package-lock.json

exercises/exercise5/twitter-api/package.json

exercises/exercise5/twitter-api/public/stylesheets/style.css

exercises/exercise5/twitter-api/routes/api/v1/Users.js