Fix submodule init issue

[soheilshahrouz]

Solves this issue

Since sockpp uses ssh to clone the repo, ssh keys need to be set up. Alternatively, we can use https for cloning the repo.

[soheilshahrouz]

Related to this PR is this stackoverflow answer

[AlexandreSinger]

Ah I see what happened here. When you use a git@ url for the repo, it requires that you have a git shh key setup (which is a good idea btw). If you use the https:// version you do not; however if you wish to push to the repo you will not be able to login. @soheilshahrouz I think you have a good point turning this into a https:// since the general user will just be pulling (not pushing anything); and so we would not require people to have an ssh key if they want to build VTR.

I am excited to see what gnarly things this will do once people rebase this change. But it must be done.

[vaughnbetz]

Seems logical since we do this for other submodules. @w0lek let us know if you have any concerns.

[w0lek]

Seems logical since we do this for other submodules. @w0lek let us know if you have any concerns.

@vaughnbetz
i am fully ok with that change.
FYI: i will update end user documentation PR comments very soon, i am keeping an eye on it, just busy with other stuff right now.