Cache all the mongodb/version folder (parse-community#2336)

* Cache all the version folder

* list cache

.travis.yml

@@ -7,6 +7,7 @@ services:
 addons:
  postgresql: '9.4'
 before_script:
+ - ls -al "$HOME/.mongodb/versions"
  - psql -c 'create database parse_server_postgres_adapter_test_database;' -U postgres
 env:
  global:
@@ -24,7 +25,7 @@ branches:
  - /^[0-9]+.[0-9]+.[0-9]+(-.*)?$/
 cache:
  directories:
- - "$HOME/.mongodb/versions/downloads"
+ - "$HOME/.mongodb/versions"
 after_script: "./node_modules/.bin/codecov"
 deploy:
  provider: npm