update_sqlite.py will add ZIM even if they are already there.

[letompouce]

Scenario:

• Visualize: a new container is created, ansiblecubepp runs, installs packages and ZIM.
• The hypervisor is rebooted, or the container is stopped.
• The container is started: ansiblecubepp will run again, and the package_management role will run updatesqlite.py again.
• update_sqlite.py will re-add the ZIM to the database
• ZIM cards are shown twice in the ideascube web interface.

The update_sqlite.py script should not add these ZIM if a previous run already added them.