Makes submodules point to https urls

.gitmodules

@@ -68,10 +68,10 @@
 	url = https://github.com/chriskempson/base16-vim/
 [submodule "bundle/ultisnips"]
 	path = bundle/ultisnips
-	url = git@github.com:SirVer/ultisnips.git
+	url = https://github.com/SirVer/ultisnips.git
 [submodule "bundle/vim-snippets"]
 	path = bundle/vim-snippets
-	url = git@github.com:honza/vim-snippets.git
+	url = https://github.com/honza/vim-snippets.git
 [submodule "bundle/fzf.vim"]
 	path = bundle/fzf.vim
 	url = https://github.com/junegunn/fzf.vim.git