IDEX-1517 User Preferences retrieved is not what has been persisted previously, fixing toMap method that was setting the json representation of the value instead of the real value (unescaped)

Task-Url: https://jira.codenvycorp.com/browse/IDEX-1517
Merge pull request #37 from sunix/IDEX-1517

IDEX-1517 User Preferences retrieved is not what has been persisted prev...