Fix chirp mass range for 150914 to correct values for *detector frame*.
Update the uniform prior limits on the chirp mass in the GW150914.prior
prior file to reflect the detector frame chirp mass (from GW150914-properties paper, the 90% interval on detector frame chirp mass is 28.5 - 32.5 MSun; see Table 1 of Abbott, et al. (2016).