FIX: Properly check bass & treble arguments for False
FIX: Properly check bass & treble arguments for False

Previously, we did `if bass:` which wouldn't function correctly if the
developer did `soco.bass(0)` (set the bass to 0), since the 0 value
would be interpreted as False rather than 0.

fxstein/SoCo,SoCo/SoCo,oyvindmal/SocoWebService,intfrr/SoCo,petteraas/SoCo,TrondKjeldas/SoCo,lawrenceakka/SoCo,DPH/SoCo,bwhaley/SoCo,KennethNielsen/SoCo,dsully/SoCo,oyvindmal/SocoWebService,fgend31/SoCo,jlmcgehee21/SoCo,fxstein/SoCo,lawrenceakka/SoCo,bwhaley/SoCo,simonalpha/SoCo,petteraas/SoCo,dsully/SoCo,SoCo/SoCo,petteraas/SoCo,bwhaley/SoCo,xxdede/SoCo,dajobe/SoCo,flavio/SoCo,jlmcgehee21/SoCo,KennethNielsen/SoCo,dajobe/SoCo,meska/SoCo,DPH/SoCo,xxdede/SoCo,intfrr/SoCo,dundeemt/SoCo,TrondKjeldas/SoCo,xxdede/SoCo,dundeemt/SoCo,meska/SoCo,fgend31/SoCo,simonalpha/SoCo,flavio/SoCo,TrondKjeldas/SoCo