Fix a typo (#2563)

Update connectionPrefix with collectionPrefix

Author: dharamgollapudi

src/ParseServer.js

@@ -143,7 +143,7 @@ class ParseServer {
     Parse.initialize(appId, javascriptKey || 'unused', masterKey);
     Parse.serverURL = serverURL;
     if ((databaseOptions || (databaseURI && databaseURI != defaults.DefaultMongoURI) || collectionPrefix !== '') && databaseAdapter) {
-      throw 'You cannot specify both a databaseAdapter and a databaseURI/databaseOptions/connectionPrefix.';
+      throw 'You cannot specify both a databaseAdapter and a databaseURI/databaseOptions/collectionPrefix.';
     } else if (!databaseAdapter) {
       databaseAdapter = new MongoStorageAdapter({
         uri: databaseURI,