calculate CRC32 using ethernet standard
RIOT coding conventions
EXTI: add code to init exti and handle them
wrap isr_exti handler by "extern C{}"
rename hl_crc to MB1_CRC
rename hl_crc to MB1_CRC
add all exti line in MB1 system
Merge pull request #2 from dangnhat/hien_dev

Import CRC32 lib using ethernet standard and EXTI lib