Open your user key-bindings (in OSX this is Sublime Text -> Preferences -> Key Bindings - User), and put

  [
    { "keys": ["ctrl+tab"], "command": "next_view" },
    { "keys": ["ctrl+shift+tab"], "command": "prev_view" }
  ]

The default behaviour is to switch tabs in a "last used" order. To change it, add this to your key bindings:

{ "keys": ["ctrl+tab"], "command": "next_view" }, { "keys": ["ctrl+shift+tab"], "command": "prev_view" }

You hold Ctrl (or Shift+Ctrl) while you tab to cycle all the way through all your tabs. The first time you press the combination, it switches to the last tab you were in. This is how it is in version 2, anyway.