Made 'viridis' the default theme, as per #3.

• Introduced packrat for better dependency tracking
• Made sure it works with ggplot2 2.1.0, which is the latest in CRAN as of 2016-10-20

colormap 0.1.2

• Added ability to generate custom palette.

colormap 0.1.1

• Added code to evenly distribute colors over the whole range of the palette.
• Added Input Validation.
• Added scale_fill_colormap and scale_color_colormap for ggplot2.

colormap 0.1.0

• Added a NEWS.md file to track changes to the package.