provide some rake tasks to edit the cloud config

rake cms:cloud_config:edit
rake cms:cloud_config:download
rake cms:cloud_config:upload

The edit task is a highlevel task. It builds upon download and upload and spawns your $EDITOR between those to actually edit the file.

Local backups of the uploaded config are stored in tmp/ with a timestamp suffix.
updates README and CHANGELOG
extend comment on why we use JSON instead of MultiJson pretty
Merge branch 'feature/cloud_config_edit' into develop

* feature/cloud_config_edit:
  extend comment on why we use JSON instead of MultiJson pretty
  updates README and CHANGELOG
  provide some rake tasks to edit the cloud config