Added I2C driver and sensor drivers (ADXL346, MAX44009, SHT21) for the OpenMote-CC2538 platform.
Merge branch 'develop' of https://github.com/OpenMote/openwsn-fw into develop
Updated the I2C driver and the ADXL346 and MAX44009 drivers.
Modified .gitignore file to avoid committing temporary files.
Renamed openmote into cc2538. This will need to change again once we update the naming convention for chips and platforms.
Moved the I2C and SPI drivers under the board directory. Updated the header of the I2C driver.
Updated the I2C driver for the CC2538 platform.
Merged OpenWSN upstream.
Merge pull request #112 from OpenMote/develop

committing missing I2C driver for OpenMote-CC2538 board