This commit adds the php-json package.

The json features of php have been moved to a separate package in the following distributions:
  - Debian >= 8 (jessie)
  - Ubuntu >= 13.04

Changes:
  - Added json.sls
  - Updated map.jinja
  - Updated README.md
Merge pull request #13 from taion809/feature_addJson

This commit adds the php-json package.