Change submodule paths to https://
Change submodule paths to https://

This is required to ensure anyone can clone the public project without
authenticating.

picoCTF/picoCTF-platform,royragsdale/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,picoCTF/picoCTF,jedav/picoCTF-platform,royragsdale/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,picoCTF/picoCTF,royragsdale/picoCTF,jedav/picoCTF-platform,royragsdale/picoCTF,royragsdale/picoCTF,picoCTF/picoCTF,picoCTF/picoCTF,picoCTF/picoCTF-platform