Resolve "SubjectDetails management"

Closes #5 (closed) -- First commit, 90% done the assignment due is till tommorow midnight, tommorow everything will be done, please check for conflicts and threads to be resolved. The subject list page works, the subject edit works I have just stumbled across a minor problem, when iterating the books i cannot edit them because i use th:each and input throws me an error, i will allow users to remove a book, and add another book option instead of editing the book list as it is done in the Subject, will that be okay ?