revert to earlier version of silex, because I can't find a good, recent, Postgres PDO package for later lessons

Author: jonmountjoy

composer.json

@@ -1,9 +1,9 @@
 {
  "require" : {
- "silex/silex": "2.0.2",
- "monolog/monolog": "~1.7",
- "twig/twig": "^1.19",
- "symfony/twig-bridge": "3.1.3"
+ "silex/silex": "^1.3",
+ "monolog/monolog": "^1.4",
+ "twig/twig": "^1.8",
+ "symfony/twig-bridge": "^2"
  },
  "require-dev": {
  "heroku/heroku-buildpack-php": "*"