Add options to remove local files download and don't show warnings and infos in process

[guisouzabr]

Hi! I work using this plugin every day, the project which I'm working for have a lot of relations, entities, etc (including a lot deleted relations), so process.js need some time to run, with the warnings and info in this file we need 40 minutes to run all process, removing the warnings and infos we have something close to 2 minutes. It's a big improve to a easy mod.... so I decided to code it like an option to the plugin (you can use it just modifying the gatsby-config with the flags). another flag I decided to create it's to download or not the files to local... in my project we don't use downloaded files.... I think this flags can be very helpful for a lot projects.

PS: The default behavior doesn’t change for all flags (you don't need to use the flags...), if you don't use the flags, your project will run like before this commit...

It's only suggestions, feel free to accept or not.

Thanks!