Change 'command-t' submodule URL

Update command-t submodule url to use github, since the original
repository apparently stopped working.
Update submodule references

Updated references to:
                           command-t
                           seoul256
                           syntastic
                           tagbar
                           tlib_vim
                           vim-bundler
                           vim-colorscheme
                           vim-fugitive
                           vim-haml
                           vim-rails
                           vim-ruby
                           vim-snipmate
                           vim-snippets