update priors on diskCA and vcirc from empirical results in model B

replaced vcirc with log10(vcirc) in pars list so that prior is
lognormal on vcirc with scatter 0.06 dex, based on e.g. Reyes++ 2011.

Change width of gaussian prior on diskCA from 0.1 to 0.05 based on
e.g. Padilla & Strauss 2008 and Unterborn & Ryden 2008.