must pop() header kwargs, or ImageHDU.read() chokes

I encountered this when reading an image and header via:

python -c "import fitsio; fitsio.read('wise-frames/6a/03406a/221/03406a221-w3-int-1b.fits', header=True)"

The ImageHDU class's read() method does not accept kwargs, so we have to pop off the header= kwargs first.