adapted listquerybuilder to use case insensitive like on all columns

tests still need to be updated. i've already created an issue: https://github.com/sulu-cmf/sulu/issues/88

- [x] test coverage
- [x] finished the code
- [x] gathered feedback for my changes

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none