Fixed minor error in readme

'git clean -fdx' only erases untracked files. It doesn't erase
all changes (as incorrectly stated in one place).
Updated browser versions
Updated to-do
Modified Karma config to use expect.js plug-in rather than including expect.js directly
First stab at testing issue where IE 8 doesn't detect mouseup events on window
Implemented setCapture() spy for testing mouse drags that leave window on IE 8
Finished first draft of test for code to handle drags leaving window on IE 8
Modified client test to require drawingArea mouse handler on IE 8