set custom headers

[sajjadmrx]

[Keivan-sf]

It looks good but we currently don't need to define a function for custom headers since we are using a static one.

However it might be the case in future specially if we are to be forced to use a different method for downloading. Until then, I have to close this pr

[Keivan-sf]

How ever the changes on test commands looks good. If you can revert other commits and only keep test-related ones we can just merge this pr