Modify Uno "lock" bits in boards.txt to make bootloader readable by

sketches.  Part of http://code.google.com/p/arduino/issues/detail?id=554

Author: WestfW

hardware/arduino/boards.txt

@@ -10,7 +10,7 @@ uno.bootloader.extended_fuses=0x05
 uno.bootloader.path=optiboot
 uno.bootloader.file=optiboot_atmega328.hex
 uno.bootloader.unlock_bits=0x3F
-uno.bootloader.lock_bits=0x0F
+uno.bootloader.lock_bits=0x2F
 uno.build.mcu=atmega328p
 uno.build.f_cpu=16000000L
 uno.build.core=arduino