tests: add pattern for short lgplv2.1 header

Add the license checker pattern which is advertised in our wiki.
Merge pull request #1396 from LudwigOrtmann/lgplv2.1-short

tests: add pattern for short lgplv2.1 header
cpu:cortex_common: add core_panic function
cpu: initial import of stm32f1
cpu:stm32f1: license cleanup and restructuring
cpu:stm32f1: add st header definitions
compiles but doesn"t link
intermediate commit
change to cortex_m3_common
removed all *not* needed header files
intermediate commit, some fixes to timer
fixed flashing scripts
solve PendSV interrupt issues
define TRANSCEIVER_BUFFER_SIZE
Makefile cleanup
progress on SPI but not fixed yet
addressing @OlegHahm comments
vlacklisting iot-lab_M3 for some examples
fix rpl_udp example, insufficient_ram!?
fix iot-lab_M3 drivers Makefile