cpu/nrf51822: fixed gpio driver
boards: added LED macro for pca1000 & yunjia-nrf
sys/net/ccn_lite/README.md change wording + add ACM ICN reference

sys/net/ccn_lite/README.md fix encoding
make: del no-delete-null-pointer-checks for clang++

This PR enables the use of clang++ to compile C++ projects by adding
`CXXUWFLAGS += -fno-delete-null-pointer-checks`, if `${CC}` understands
`-fno-delete-null-pointer-checks` but `${CXX}` does not.
core: Provide functions for different byte orders

Rationale: see #1586.
tests: Add unittests for byteorder.h
tests: fix bad copy+paste in tests-core.h
make: Allow for include of modules outside of the RIOTBASE path
atmega_common: add ENOTSUP and ECANCELED to errno.h
pkg/Makefile.http: complete Makefile-example
native: add two more syscall declarations
Merge pull request #1746 from authmillenon/external_modules

make: Allow for include of modules outside of the RIOTBASE path
cpu/stm32f1: fixed gpio driver

- changed #ifdef to #if for device filter
- guarded file in case no GPIO device is defined
- added guards around interrupts
Merge pull request #1750 from backenklee/make_fix

pkg/Makefile.http: complete Makefile-example
Merge pull request #1751 from LudwigOrtmann/native_syscalls_p2

native: add two more syscall declarations
drivers: Provide basic interface for all network devices
tests: Add functionality test for netdev_base
Merge pull request #1752 from haukepetersen/fix_stm32f1_gpio

cpu/stm32f1: fixed gpio driver
Merge pull request #1492 from authmillenon/net-dev-base

drivers: Introduce a general interface for network device drivers
tests: fix netdev test