added new board f4vi1
Merge pull request #1933 from StefanPfeiffer/add_board_f4vi1

board: added support for f4vi1
lsm303dlhc: initial import of lsm303dlhc driver

TODO: Accelerometer does not return valid values yet
SQUASHME: addressing comments
board/iot-lab_M3: added I2C ISR defines
cpu/stm32f1: fixes to i2c driver

- fixes BUSY on initialization