exclude image recipes for now
add basic recipe for qemux86. To be used as a general recipe in the future.
reenable all recipes
add recipe for autoconf-2.13 which Mozilla does insist on. Thanks to angstrom for teh base recipe. I just modified it a bit.
b2g requires autoconf-2.13 for building
at least on x86, yasm is required. I guess this can be specified differently in the future.
change readme to reflect the current state