Update LabEnv to use BASE database capabilties instead of SQLite

[Nicklas Nordborg]

The LabEnv extension currently uses an SQLite database for storing measurements.

BASE 3.4 will include a new feature that allows extensions to get access to part of the database for their own storage needs. See ​http://base.thep.lu.se/ticket/1892

I think we should drop the SQLite implementation and switch to what BASE provides.

Basically this means we use Hibernate and HQL and configure the LabEnvironmentData and an @Entity and then replace SQLite-related functionality in LabEnvironmentStorageUtil class to use Hibernate instead.

It would also be nice if we could automatically import the existing SQLite database to BASE automatically. But this means we will need to keep SQLite around for an extra release.