MAFA-5: After adding functionality to query api for a max of 50 requests for review data. Also fixed an issue where system breaks when there is no ratings at all for any product and the database manager tries to calculate the average rating of all apps. Also added functionality to clear the entire database when the last query was over 24 hours previous to use

Signed-off-by: unknown <cnwnh1@cnwcb5a.cnw.co.nz>