sunday edits

1. short-circuit updates on round-trip to wink api
2. add motive distance (should be client-derived, but really useful)
3. oneshot in fahrenheit (for now)
better smoke detector support
add displayUnits to place actor
add initial support for yocto-4-20mA-Rx
new svgs - sensor-co + sensor-no2 #35
normalize all validate_observe/observe/perform functions

and initial (but incomplete) support for the roomba
distance is Km not m
better use of customary units in oneshot
change superscript to subscript #35
remove irobot/floor from CHANGELOG

(it won't be ready for the 1.4 release)
meters or feet
remember logged in users
ditto
Fix for issue #112
fix flower-power-cloud defaulting on incomplete response...
not needed (yet)
Fix typo, update home display when devices change