Question mark in file name causes issues on Windows machines

[larjohn]

A simple removal of the question mark in demos/israel/aggregate?dataset=israel makes the OpenSpending Viewer buildable in Windows machines.

I know this is not a priority, but is simple enough to be a blocker.

[pwalsh]

Hey @larjohn thanks. Those demos are really old, and we are kind of slowly updating bubbletree now to go with our new viz. We'll be happy for a pull request if you can :).

[larjohn]

Commited #45