Make some Job fields longer

[maxceem]

• Make description field technically unlimited, instead of default 255 chars
• Make title field max length 128 insated of 64, as it was too short
• Explicitly define the length of all VARCHAR fields for 2 reasons:
  • npm run init-db force would create DB schema, and if we don't define explicit length for VARCHAR in model definitions, then default 255 length would be used which is not always what we want
  • even if we keep the default length, still explicitly define 255 to keep us aware of the maximum length, we have to make sure, that Joi has validation rules which do not pass data that is not accepted by DB, to keep things clear

[maxceem]

Done via PR #110

[maxceem]

It was tested on DEV and works well. For example, this job 'https://api.topcoder-dev.com/v5/jobs/5e809cde-e001-4f80-867d-0d4c4239b870' has a description of more than 65000 characters long: