Remove collection prefix and default mongo URI (#1479)

* Remove collection prefix from DB Controller

* Remove collection prefix from cache

* Revert "Remove collection prefix from cache"

This reverts commit 529d67dd617b64c69c36a8a63382456e95edcab8.

* Remove knowledge of default mongo URI from Parse Server

* Remove adaptive collection paramater from deleteFields

* Tidy up DBAdapter.js

src/DatabaseAdapter.js

@@ -18,17 +18,10 @@
 import DatabaseController  from './Controllers/DatabaseController';
 import MongoStorageAdapter from './Adapters/Storage/Mongo/MongoStorageAdapter';
 
-const DefaultDatabaseURI = 'mongodb://localhost:27017/parse';
-
 let dbConnections = {};
-let databaseURI = DefaultDatabaseURI;
 let appDatabaseURIs = {};
 let appDatabaseOptions = {};
 
-function setDatabaseURI(uri) {
-  databaseURI = uri;
-}
-
 function setAppDatabaseURI(appId, uri) {
   appDatabaseURIs[appId] = uri;
 }
@@ -61,26 +54,21 @@ function getDatabaseConnection(appId: string, collectionPrefix: string) {
     return dbConnections[appId];
   }
 
-  var dbURI = (appDatabaseURIs[appId] ? appDatabaseURIs[appId] : databaseURI);
-
-  let storageAdapter = new MongoStorageAdapter({
-    uri: dbURI,
+  let mongoAdapterOptions = {
     collectionPrefix: collectionPrefix,
-    mongoOptions: appDatabaseOptions[appId]
-  });
+    mongoOptions: appDatabaseOptions[appId],
+    uri: appDatabaseURIs[appId], //may be undefined if the user didn't supply a URI, in which case the default will be used
+  }
+
+  dbConnections[appId] = new DatabaseController(new MongoStorageAdapter(mongoAdapterOptions));
 
-  dbConnections[appId] = new DatabaseController(storageAdapter, {
-    collectionPrefix: collectionPrefix
-  });
   return dbConnections[appId];
 }
 
 module.exports = {
   getDatabaseConnection: getDatabaseConnection,
-  setDatabaseURI: setDatabaseURI,
   setAppDatabaseOptions: setAppDatabaseOptions,
   setAppDatabaseURI: setAppDatabaseURI,
   clearDatabaseSettings: clearDatabaseSettings,
   destroyAllDataPermanently: destroyAllDataPermanently,
-  defaultDatabaseURI: databaseURI
 };