Added "commons"  module and additional exceptions.
Merge branch 'master' of https://github.com/craftercms/studio3

Conflicts:
	api/src/main/java/org/craftercms/studio/api/exception/ItemNotFoundException.java
AuditController
Merge branch 'master' of github.com:craftercms/studio3
Move DTO, Exceptions,Filters & extractors, Change poms