Initial gsm files. On very early stage. Not working.
Merge branch 'master' into gsm
Merge branch 'master' into gsm
GSM lib config
Added ringbuffer implementation. Added not-yet-ready gsm library
Added ringbuff.c to build
Merge branch 'master' into gsm
Added delay_ms() function and ruuvi.delay_ms() for lua
ruuvi_build.sh now removes also flash images
New functions for ringbuffer: _get_raw() and _remove()
First implementation of GSM driver.

Basic state handling and command/response handler.
Fixed GSM driver hang up problem when sending AT commands.

Known problems still exist:
 * Buffer imlementation cannot be circular, need linear to use with <string.h> functions.
 * Needs another buffer to catch output from commands.
 * Needs new function that waits for a specific answer from AT cmd.
Updating GSM driver.

Better AT cmd handling.
Added basic pattern searching.
SMS sending now works.
Added GSM example script
Merge branch 'gsm'