Saving params for task

[shashwatrathod]

• Created a new MySQL table - worker_params that stores workerID and JSON-stringified set of params.
• Added two new methods in db/annonUser.js to save params for a user in the db and get params for a particular worker from the db.
• Added two new helper methods in filters to check for parameters in body and query params. This was done for:
  a. Readability
  b. Avoiding confusion in knowing where the parameter should actually belong
• Added a new POST route /api/tasks/saveParams that..well..saves the parameters supplied to it in the db.
• When the taskController loads, we now hit /api/tasks/saveParams to save the set of parameters that the worker entered the page with.