Merge pull request #16 from lpotter/master

[sensorfw] get rid of mce buildtime requirement
[sensorfw] Actually install the message handler.
[sensord] Always restart.

We never want to not be running. If someone wants to stop sensord, they can stop
the service through systemctl, the same as other system daemons.
Merge pull request #17 from rburchell/master

Fixups.
bump version to 0.7.3.20