Add support for driver firmware in Makefile, Cubieboard LEDs, wifi/ad-hoc

[MagnusS]

Changes:

• LED support enabled in kernel (controlled through /sys/, see http://linux-sunxi.org/Cubieboard/Programming/StatusLEDs)
• / mounted as noatime,nodiratime in /etc/fstab
• FIRMWARE-variable added to Makefile, linux-firmware cloned automatically, instructions in README.md updated
• drivers and firmware enabled for TP-Link TL-WN725N (r8188eu) and Netgear WNA1100 (ath9k_htc)
• enabled BATMAN_adv module for ad-hoc routing
• installs packages iw (for wifi) and batctl (batman control tool) to image
• updated .gitignore