Add method to write plaintext lightcurve
Add method to write plaintext lightcurve

This method just creates a file to hold the lightcurve and dumps the
lightcurve array made by one of the bolometric lightcurve methods.

TODO: Add code to each of the lightcurve methods which makes an array of
JD, Phase, Lbol, Lerr

JALusk/SuperBoL,JALusk/SNoBoL,JALusk/SNoBoL