Added javadoc comments to modified files.
JavaDoc added for methods in several classes

JavaDoc completed for the following classes:
Admin
DatabaseController
CabinDatabaseController
merge Herman's into master
removed an unused variable, as suggested by Herman in previous commit
fixed merge conflicts, and merged in arne's changes
added javadoc to the admin overview controller
Added javadoc to the email view controller
added javadoc to the login view controller
updated the javadoc in the register view controller
Added javadoc to the report overview controller
added javadoc to the custom cabin cell
added javadoc to the custom report cell
fixed a bug which made the wrong username appear in the top menu
Merge branch 'andreas' of https://github.com/karlpa/it1901 into andreas