uploader: ignore bad character encodings for older bootloaders

this prevents the uploader from throwing an exception with older
bootloaders
hmc5883: properly reset mag to normal state on calibration fail

and add current output in "hmc5883 info"
tone_alarm: Added arming failure tone
Compile hotfix for master
Merge pull request #801 from PX4/hmc_fix

hmc5883: properly reset mag to normal state on calibration fail
Merge pull request #802 from PX4/arming_fail_tune

tone_alarm: Added arming failure tone
Merge branch 'master' into rc_timeout