[flow] allow casting from bool to string (results into '1' or '0')
[flow] allow casting from bool to string (results into '1' or '0')

Change-Id: Ic0a93a8a5cac7d61c9413340d3458ec67ce73891

christianparpart/x0,xzero/x0,xzero/x0,xzero/x0,xzero/x0,christianparpart/x0,xzero/x0,christianparpart/x0,christianparpart/x0,christianparpart/x0,xzero/x0,christianparpart/x0,christianparpart/x0