Modify www6308ui.sakura.ne.jp.json to install nagios.
Merge branch 'nodes'
Install python-demjson package in order to test the json format validity.

  This fixes #36.
Check the json file format validity when testing.

  Chef solo fails often because the json file format is invalid.
  Before commiting, check the json file format validity.

  This commit fixes #39.
Merge branch 'dev'