idrac_firmware - add proxy option

[markatdxb]

hi, any chance you could add option to specify http proxy as part of the idrac_firmware module ? We need it in order to access donwloads.dell.com thanks

[benfab]

We are also hitting this limitation, so very keen on having this option avaible as part of the idrac_firmware module.

[sdx23]

We're as well missing that feature and would be glad to see it available.

[anupamaloke]

Closed by #458