Add files for onekey(issue #56)

- https://github.com/tmk/tmk_keyboard/issues/56
Change ADB scan delay 12ms
Add ADB protocol files from blargg's work

- <http://geekhack.org/index.php?topic=14290.msg1070604#msg1070604>
Merge blargg's fix into adb.c

- <http://geekhack.org/index.php?topic=14290.msg1075201#msg1075201>
Delete MOUSEKEY_DELAY_TIME in config.h
Add USE_LEGACY_KEYMAP in config.h of ps2_usb and IIgs
Merge branch 'onekey'
Tweak time values of busywait PS/2
Fix PS/2 mouse support
Add cli() to protoect ADB critical timing part
Fix ADB led_set(); remove delay

- the 100ms delay causes keystroke drop; this is observable with
  pressing Numlock key on AEK repeatedly
- without the delay LED sync problem doesn't occur now
Disable BOOTMAGIC and fix debug prints of adb_usb
Remove tentative files from blargg
Wait for USB starting up to make debug print available
Fix delay of PS/2 mouse init
Add PS/2 mouse configure to onekey
Fix to build ps2_mouse with both LUFA and PJRC

- change API of ps2_mouse; ps2_mouse_task()
- remove mouse_report from host.c
Add build options of ps2_mouse
Add tap toggle modifiers

Including documentation.
Fix interrupt version of ps2.c