fix(travis): Use MariaDB credentials from site_config.json

.travis.yml

@@ -58,7 +58,7 @@ before_script:
   - sed -i 's/9000/9001/g' sites/common_site_config.json
   - bench start &
   - bench get-app erpnext $TRAVIS_BUILD_DIR
-  - bench --site test_site reinstall --mariadb-root-username root --mariadb-root-password travis --yes
+  - bench --site test_site reinstall --yes
 
 after_script:
   - pip install python-coveralls

.travis/site_config.json

@@ -6,6 +6,7 @@
  "mail_login": "test@example.com",
  "mail_password": "test",
  "admin_password": "admin",
+ "root_login": "root",
  "root_password": "travis",
  "host_name": "http://test_site:8000",
  "install_apps": ["erpnext"]