sys/net/ccn_lite/README.md change wording + add ACM ICN reference

sys/net/ccn_lite/README.md fix encoding
tests/periph_spi: let build fail without SPI
make: introduce and use periph_spi feature
Merge pull request #1809 from LudwigOrtmann/Makefile.features-SPI

make: periph_spi feature
drivers: added low-level I2C driver interface
cpu/stm32f1: added low-level I2C driver
board/iot-lab_M3: added I2C device definitions
board/iot-lab_M3: added features
tests: added i2c driver test
Merge pull request #1785 from haukepetersen/add_stm32f1_i2c

cpu/stm32f1: added I2C interface&implementation
drivers: added driver for ISL29020 light sensor
board/iot-lab_M3: added ISL29020 interface defs
tests: added test for ISL29020 light sensor driver
Merge pull request #1786 from haukepetersen/add_driver_isl29020

drivers: added driver for ISL29020 light sensor
net: Initial import of a global packet buffer
Merge pull request #1716 from waehlisch/master

Update CCN-lite Readme
Merge pull request #1638 from authmillenon/packetbuf2

net: Initial import of a global packet buffer
periph.cpuid: Add central documentation for CPUID_ID_LEN
auto_init: use full hash to configure radio address

Since the 4-byte CPU ID on native is in most cases generated from the 2-byte
PID of the native process, choosing the lower half of the hash of the CPU ID to
set the radio address led to always setting it to the hash of 0 in this
cases. This changes it to use both halves of the hash and taking the
modulus so this corner cases can be avoided.
auto_init: reduce scope of iface