core: sched.c did not compile with DEBUG=1
boards/cc2538dk: allow the application's makefile to override the UPDATE_CCA parameter, for example:
CFLAGS += -DUPDATE_CCA=0
cpu/sam3x8e: added interrupt mode to uart driver
board/arduino-due: added missing UART defines

- added port defines to periph_conf.h
- added feature to Makefile.features
board/udoo: added missing UART defines

- added defines to periph_conf.h
- added UART feature to Makefile.features
cpu/sam3x8e: made UART0 work by editing syscalls
Merge pull request #1482 from haukepetersen/fix_sam3x_finished_uart

cpu/sam3x: completed low-level UART driver
Merge pull request #1981 from locicontrols/update-cca

boards/cc2538dk: allow the application's makefile to override UPDATE_CCA
Merge pull request #1962 from Kijewski/sched-fix-debug-1

core: sched.c did not compile with DEBUG=1
core/sched: unify DEBUG text syntax, nomenclature
Merge pull request #1999 from LudwigOrtmann/sched_debug_unify

core/sched: unify DEBUG text syntax, nomenclature
oneway-malloc: fix prototype for calloc

The prototype differs from stdlib
Merge pull request #2001 from OlegHahm/oneway_calloc_signature

oneway-malloc: fix prototype for calloc
Add UBJSON library
tests: add UBJSON unittests
Add UBJSON example