buzz defconfig: more net filter options

Enables target ttl for ipv4 and enables ipv6 filtering.
iosched Kconfig: enable SIO

Allows the configuration of the SIO scheduler in the
kernel config file and Makefile.
buzz defconfig: enable deadline and sio schedulers

Enables the deadline and sio IO schedulers in the default config.
sio-iosched: update to version 0.2

Updates the sio scheduler to version 0.2.
buzz_defconfig: enable xz

Enables the xz compressor/decompressor in the kernel default config.
buzz_defconfig: update timestamp