JID should be able to handle more than one database connection

Description
Currently JID is working with exactly one database connection. If there are several JobScheduler instances with different database connections, it is not possible to show these in one JID
Desired behaviour
It should be able to change the connection inside the application (only one connection has to be active at the same time).
Implementation
The different database connection are stored in files with the naming schema

hibernate.cfg.<name>.xml e.g. hibernate.cfg.oracle.xml

All files that follows this naming convention are shown in a combo box in JID. The file hibernate.cfg.xml will be shown with the name default. If there is only the default file, the combo box will not be shown.