Temporary H2GIS db (discussion)

[ebocher]

Add a method to create from a WPS script a temporary H2GIS database.
When the script is finished (after a delay) or if it's returned an error the temporary database is deleted.

WPSUtilities.getTemporaryFolder() -> Return a temporary folder used by the WPS service

WPSUtilities.createTemporaryDB() -> Create a new H2GIS database stored in the temporary folder.