Merge pull request #164 from Wendly/unique

Support Column.uniqueGroups
Made Column name optional. If not explicitly defined in the annotation, it defaults to the name of the corresponding field in the Model.
Made Column name optional.

If not explicitly defined in the annotation, it defaults to the name of the corresponding field in the Model.
Merge pull request #167 from harward/master

Make Column name optional.
Support Column.indexGroups