Added matplotlylib.py module and an example usage file (plot_sin.py)

The module matplotlylib is intended to be a wrapper for matplotlib
figures. This module currently supports ONLY scatter plots made in
matplotlib--more details below.

An example call to re-plot a figure created in matplotlib looks
something like this:

matplotlylib.plot(mpl_figure_obj, plotly_username, plotly_api_key)

The python file, plot_sin.py, gives a quick example of how to use the
call.

Currently supports:

- Plots with a SINGLE axis
- Multiple lines (traces), per axis
- Some legend support
- Labeling, including xaxis, yaxis, and plot title
- Marker symbol transpositions
- Line style transpositions
- Pixel size of figure
- Line/Marker colors
- xlim/ylim conserved
- a few other things