Move MongoDB Connection string to config file (#18)

backend-services/feed-service/app/models/MongoDBClient.scala

 package models
 
+import com.typesafe.config.ConfigFactory
+
 import org.mongodb.scala.{MongoClient, MongoDatabase, MongoCollection, Document, FindObservable, Observer, Observable}
 import org.mongodb.scala.model.{Filters, Projections, Sorts}
 import org.bson.conversions.Bson
@@ -15,6 +17,9 @@ import scala.util.{Success, Failure, Try}
  * @constructor Creates a new instance of the MongoDBClient class.
  */
 class MongoDBClient {
+    // Loads the default configuration
+    private val config = ConfigFactory.load()
+
     // Connects to a MongoDB Client when class is constructed
     private var client: MongoClient = this.connect()
 
@@ -24,7 +29,7 @@ class MongoDBClient {
      * @return A MongoClient instance.
      */
     def connect(): MongoClient = {
-        MongoClient("mongodb://localhost:27017/")
+        MongoClient(config.getString("mongo.default.url"))
     }
 
     /**

backend-services/feed-service/conf/application.conf

-# https://www.playframework.com/documentation/latest/Configuration
+# MongoDB Connection Strings
+mongo.default.url="mongodb://localhost:27017/"