APY-112: Make authentication user name case insensitive

converted to lowercase before comparing
APY-47: Refactor CDM to include content metadata and make it extensible

added metadata for publishing images
cleanup
APY-112: Make authentication user name case insensitive

added str.lower instead of sqlalchemy lower func (review comments)
Merge pull request #526 from cristidomsa/auth

APY-47: Refactor CDM, APY-112: Make authentication user name case insensitive