updates styles for flash messages
adds cancan gem to project
adds three roles administrator, developer and user
adds Ability Model
Adds exception handling for cancan in application controller
Adds authorization to jobs controller
adds placeholder method for the document sharing feature
adds authorization for document controller
adds authorization for nodes controller
shows only user's nodes in node overview
adds authorization to workflow controller
adds authorization to workflow controller
fixes a bug where documents were displayed that do not belong to the current user if the user added document to a job
adds dummy methods for further features
fixes typo
adds placeholder for future features
adds two seed documents to the seed user