Disallow empty department or position #40

+ Display error when trying to add empty categories
Merge pull request #96 from azrul/issue_40

+ Disallow empty department or position #40
+ Display error when trying to add empty categories
Fix file headers with correct package names

Some package name were copy/pasted and not properly written before
Merge pull request #97 from azrul/copyright_update

Fix file headers with correct package names