Adds var $id_dust_sensor and treating the default (no sensor) case.
The dust graph now works, needs cosmetics
better looking
Fix the wrong unit in the graph
Merge branch 'add_dust_curve' into dev
adds var $id_voc_sensor
Adds the VOC graph
Adds explanations about the units to be found in the xively.com/feed
Merge branch 'add_voc_curve' into dev
Change version to v0.7
Merge branch 'dev'