Add VACUUM command to database on call to importjson (optional?)

[fbanados]

Because our servers seem to still have spinning disks, accessing them can take considerable time, which turns into slow warmup times for loading up the database into file cache memory, affecting the speed of results.

Either we change database engines (which would impact our future mobile apps) or we VACUUM to minimize the size of our database after a considerable amount of modifications are made, as it happens during importjsondict. Vacuuming minimizes the size of the database, and has the convenient side effect of writing the database to storage, meaning the database is in the file cache, and should help on immediately following reboots of the system and make those fast.