Missing check for associated items when deleting jobs

[Nicklas Nordborg]

It seems like there is a missing check for "used items" when deleting jobs that are associated with a derived bioassay. The jobs are listed as not having any dependency but when trying to delete them a stacktrace appears:

ERROR: update or delete on table "Jobs" violates foreign key constraint "fkb7e746c5b92076ba" on table "DerivedBioAssays"
Detail: Key (id)=(472075) is still referenced from table "DerivedBioAssays".

DatabaseException
...at HibernateUtil.commit(HibernateUtil.java:1173)
...at DbControl.commit(DbControl.java:505)
...at Trashcan.delete(Trashcan.java:276)
...at org.apache.jsp.views.trashcan.index_jsp._jspService(index_jsp.java:161)
...at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
...at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
...at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
...at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
...

[Nicklas Nordborg]

(In [6442]) Fixes #1800: Missing check for associated items when deleting jobs