Allow users to use the crawler on the browser

[marcelovani]

I think a nice feature would be to provide an UI similar to this https://validator.w3.org/ where the users can either paste a list of urls or upload a CSV or Json file to be processed.

Tasks:

1 - Provide an upload field to let users upload CSV or Json file. 2 - A textarea field to allow people to paste a list of urls 3 - Add validation of the data in the backend