Add BadRequestException/Mapper -> HTTP 400

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Fix JavaDoc

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Fix JavaDoc

Signed-off-by: Alin Dreghiciu <adreghiciu@gmail.com>
Merge pull request #4 from sonatype/bad-request-ex

Add BadRequestException/Mapper -> HTTP 400