Language in warning on shared page is inconsistent with behaviour

[Cheddam]

Tested version: 2.x-dev

Outline

The warning banner on a shared draft page states:

You are viewing the draft state of this page, any page you navigate to will be the published state.

However, links in standard Menu()s contain ?Stage=Stage, and will prompt the user to log in, so this statement is incorrect. Either the warning or the behaviour needs to be adjusted - I'm honestly not sure which approach makes more sense at this stage.

[Cheddam]

cc/ @silverstripeux

[sachajudd]

Could be related to when we update the front-end of the warning: #83

[clarkepaul]

We have to assume that people wont have access to log in as thats the problem space we are trying to solve.

Message could be something like:
You are viewing the draft state of this page, any other page you navigate to will be the published state unless you log into the CMS.

But in addition to that I think we should remove all the staging links (except the shared page) unless the user is logged in.

[clarkepaul]

Feels like we should be doing something a little more future proof as well but not sure exactly how e.g. ?Stage=Shared-xyz