changes to the tables

Description
version allow null
avalible_from allow null

Licence
issued_by allow null

Change name of table Provider to Organization

Description 1->n Organization

Suite
delete provided_by

Tool 1->n Alternative_Title
title

Users
Mail, Login and Passord not null

Description 1->n Tool_type
Description 1->n Application_type

Description
delete User_UID (duplicate of registerd_by)

Tool_type
add sourceURI

Keyword
add sourceURI