PS_ON configurable boot state

Allows the user to select wheter or not the PSU should be turned on or
kept in standby when marlin boots
Merge pull request #630 from dumle29/Marlin_v1

PS_ON configurable boot state
Initial SAV MkI (RepRap CloneWars board) integration.

Included support for BT dongle on AT90USB boards.
Added LCD Shift Register LCD control
Included support for RepRap Clone Wars project board (SAV MKI).
Made instructions more clear.

Not sure what happened to my last commit so this includes that one + reordering the steps.
Merge pull request #632 from dbenamy/Marlin_v1

Made instructions more clear.
Fix servo control for Melzi
Corrected LCD only error

If only an LCD is defined and no menu or keyboard defined, there is a
compilation error.

Added conditional compilation.
Add (correct) missing pin definitions for Y2

I tested this and it works.
Add UUID support to M115 responses.
Added BT support on AT90USB devices

Added AT90USB device BT connectivity support using second UART.
If you have a switch on suicide pin, this is useful if you want to
start another print with suicide feature after a print without
suicide...
Implement M226 - GCode Initiated Pause

Implemented M226 as described here:
http://reprap.org/wiki/G-code#M226:_Gcode_Initiated_Pause

Waits for pin to be become either HIGH, LOW or the inverse of what it
was before. Allows printing to pause until user interaction
Merge pull request #635 from dbenamy/Marlin_v1

Add (correct) missing pin definitions for Y2
Merge pull request #636 from PrintToPeer/Marlin_v1

Add UUID support to M115 responses.
Merge pull request #637 from justuswilhelm/Marlin_v1

Fix servo control for Melzi v2.0
Merge pull request #640 from fmalpartida/SAV-MkI

Added support for BT on AT90USB devices, corrected LCD bug, added new board and LCD
Merge pull request #641 from hugokernel/master

M80 - ATX Power On related modification
Merge pull request #647 from shaggythesheep/newfeature-M226

Implement M226 - GCode Initiated Pause
Fixed compile errors from bad commits.