Add mipsel support to mic

Added support for mic. Handles detecting the MIPS architecture binaries and
installs qemu with binfmt so that mic is able to run MIPS code with qemu.

Signed-off-by: Mikko Hurskainen <mikko.hurskainen@nomovok.com>
let blkid use /dev/null as cache file

in mer SDK to generate btrfs images blkid works more reliable with no
cache file.

Signed-off-by: Reto Zingg <reto.zingg@jollamobile.com>