Add initial plotting code.

[joshbriegal]

Add plots based on Ed's Blanco 1 paper. Show data (with or without GP) Show outputted periods compared (+ GP distributions) Show phase folds. For each method:

• Show relevant plot (e.g. periodogram)
• Show phase fold on period.

Closes #17

[joshbriegal]

Todo:

• ~Add docstrings to all plotting functions.~
• ~Make lightcurve plot a little larger (height)~
• Add residuals for GP Model
• ~Title of summary plot e.g "Adopted Period: X+/-Y", or in latex font.~
• ~"Phase fold" in title not needed. "Period: X.XXXX Days"~
• ~Add units to roto object.~
• ~Zoom on LS -> length of timeseries as max possible period (could be a separate issue for calculation)~
• ~Colour consistency across plots, give each method a fixed colour.~
• ~Name of methods should be formal names -> "lombscargle" -> "Lomb-Scargle"~
• ~Just create a plot for the summary data (no method plots).~