Added sensor properties + example to reflect consistency changes#6

Merged

tannewt merged 3 commits intoadafruit:masterfrom brentru:sensor-prop

Jun 1, 2018

+28-2

Commits on May 29, 2018

created properties for tvoc, eco2. verified on hardware. changed example to reflect modifications
brentru
committed
changed baseline naming to reflect tannewt's comment
brentru
committed

Commits on May 31, 2018

made changes to reflect tannewt's review
brentru
committed