Adding basic functionality

Created functions to calculate the bolometric correction and the
luminosity. Not sure at this state whether I want the functions to
operate on individual operations (you give it a set of photometric
observations given on the same night, it gives you the luminosity) or on
the entire set of observations (load in a list or array of observations,
if spits out a bolometric lightcurve.) At this point, I'm leaning toward
individual observations, since you can always run it multiple times to
get a lightcurve.
Fixed stupid omission of colon after function def
Changed calc_lbol to return log(L, 10)

User can always change it back later, but it seems like this is the
value everyone plots bolometric lightcurves in, anyway
Changed bc_color args from arrays to floats

I think it's cleaner and more portable to have the functions work on
individual observations than on an array of observations. The output of
the code will be a single value of Lbol, and you can loop over your
observations to get a lightcurve.