[Xmonad] Small key binding change

[Donald Bruce Stewart]

I just pushed a patch that changes the bindings for
incMaster/swapLeft/swapRight.

swapLeft/Right are movement operators, that did clash with firefox's
back key. So they're now bound to:

    mod-shift-j and k

That means incMaster ops are now

    mod-comma and mod-period (the < and > keys)

Hope that's a bit more intuitive (particular 'swap', and avoids a
clash).

-- Don