adding exercise 4

exercises/exercise4/MyContacts/routes/api/v1/contacts.js

+// module that will define all routes associated with contacts
+/* In this file you will define all the routes for your api.
+You will need to define the following routes:
+1) /api/v1/contacts
+  This route will need to respond to 3 requests:
+  1) GET: it will respond with the serialized form of all the
+  contacts in your application and a response code of 200
+  /api/v1/contacts?firstName=foo&lastName=bar
+  2) GET: It will return all of the contacts that match the query paramaters
+  you pass. If none of them match you should respond with an empty array. If more than
+  one query parameter is passed, the resources that match need to match all of the 
+  conditions, e.g. if you are passing values for both the firstName and lastName then
+  your matches need to match both query parameters. Note: query params end at the end of the route,
+  and all come after the ? character and are combined with a &.
+  3) POST: it will respond to a POST request that will generate a 
+  new instance of a contact and add it to the database.
+  Your server should respond with a 201 status code and a message saying "successfully added contact".
+2) /api/v1/contacts/:id
+  This route will need to responde to 3 requests:
+  1) GET: it will respond with the serialized form of the requested
+  resource and a response code of 200. You will receive the :id from 
+  the req.params.id property. If the resource (contact) is not found in your "database",
+  then you should respond with a http status code of 404 and a message saying
+  "the resource was not found" as json.
+  /api/v1/contacts/:id
+  3) PUT: it will update the resource with the information attached in
+  the req.body property.   
+  Your route should respond with a 201 response code along with the updated
+  resource otherwise 404 with an error message of "unable to update resource".
+  4) DELETE: it will remove the contact from the collection with the matching id 
+  in the request.params object and respond with a status code of 201 along with 
+  the deleted resource in the response. If the resource is not found the route should
+  respond with a 404 error and message "resource not found".  
+
+  Hint: when sending your response you should follow the following examples:
+  res.status(404).json({error: 'Contact not found'})  
+  res.status(200).json(contacts)
+  res.status(201).json(data)  
+  */
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