Removed unused methods of Category, and simplified the existent ones.
Improved query to test if tenders exist.
Improved main view of contract.
Improved main view of entitites.

Also made it compatible with mobile and tablets.
Improved summary of contract.

Also fixed translation error of previous commit.
Made css of prices valid outside summary.
Made last contracts part of new UI of entity page.
Changed name of function and cache to allow migration.