Always close stream in readPreferences(). Fixes #729.
Merge pull request #730 from stefanbirkner/issue-729

Always close stream in readPreferences(). Fixes #729.
adding annotation validators functionality
changes after feedback
More changes after feedback

- Fixed indentation
- Simplified hasValidatorAnnotation method
- Deleted test that was covered elsewhere
Changes from more feedback
- extracted creation of annotation validator into a factory
- added thread saftey around collections
added missing documentation