[0.2] Close button on new presentation after signup

[masukomi]

After logging in for the first time it presents a dialog asking you to create a new presentation.

There is a close button on this dialog. Clicking it does nothing.

Expected:
The dialog would go away and I would be able to explore whatever portion of the UI is explorable without a presentation.

Suggested fix:
Remove the close button when the user has no existing presentations.

Alternate fix:
Provide some feedback that the user must create a presentation before proceeding.

[masukomi]

note: the X works, in this scenario (the dialog goes away) but the "close" doesn't.

It appears that closing it just makes a new presentation (with a placeholder name I think), clicking add slide appears to work fine. I'm now thinking the best solution is to remove the close button, AND the X.