Purge options

The parameters are the following:

- Purge Interval: Schedule when do you want to execute the purge
- Type of purge in database: Set how and what to purge
- Purge by days
  - Delete database before (days): Will keep data of the last (XX) days and purge the rest
  - Delete files before (days): Will keep files of the last (XX) days and purge the rest
- Purge by Free Space
  - Delete files and database on SD below (percent): Will delete stored files and data from the database until free space on the SD is more than that configured
  - Delete files and database on CAMERA below (percent): Will delete stored files and data from the database until free space on the camera is more than that configured