remove http-proxy setting from VagrantFile

[mapuri]

This issue tracks fixing the current netplugin VagrantFile to remove hardcoded http-proxy environment variables and allow their runtime specification. This shall allow netplugin demo to be run in non Cisco environments

[lexlapax]

let us know when you commit the changes back in.. want to try this out on my home box without connecting to the cisco network.

[lexlapax]

@mapuri for now, I'm just commenting out the exports in the Vagrantfile to proceed with the build.

[mapuri]

@lexlapax, yes that should work as a workaround for now.

[danehans]

@mapuri @lexlapax commenting out the ENV proxy info allowed me to spin-up my netplugin vagrant vm.

[mapuri]

Fixed by PR #5