Added I2C helper function i2c.read_from() and i2c.write_to()
Enabled I2C initialization on boot
Modifed i2c.read_from() to return number istead of string when reading single byte
Fixed sim detection on boot.
Updating build scripts.

Silenced echoing of compile commands.
Added script for building TAGS and CScope databases. Updates automatically, requires first run by hand.
Removed unused conf.lua
Configured build to use 4 threads. Faster builds.
Added TAGS to ignore file.
Added timeouts to I2C
Added gsm.power_on() and gsm.power_off()
Merge branch 'master' of github.com:RuuviTracker/ruuvitracker_fw