added views to add category to library and to add author to library

changes in views.py:
- updated add_category_post:
- - - now it supports deleted status

- added add_category_library_post:
- - - it requires 2 parameters, name and deleted:
- - - - - - if checkbox on deleted (active) was not checkd it is
considered not active (thats stupid i know it))
- - - if no name provied it does nothing and redirects to library page

- added add_author:
- - - it requires only name parameter, if it was not provided this view
does nothing, but later we will add some message to its response, when
ajax will be implemented

changes in develop_library.jinja2:
- added forms with input fields to add category and author

changes in __init__.py:
- added routes to post methods of views add_category_library_post and
add_author

changes in develop_add_category.jinja2:
- added checkbox to let user set status of the category (active or not)