Upgrade df-core

Author: alexanderko

composer.json

@@ -29,7 +29,7 @@
  "minimum-stability": "dev",
  "prefer-stable": true,
  "require": {
- "dreamfactory/df-core": "~0.25"
+ "dreamfactory/df-core": "~1.0"
  },
  "require-dev": {
  "phpunit/phpunit": "@stable"