Merge pull request #125 from ColinEberhardt/master

Removed redundant sourcemap file
A few minor tweaks

+ Changed the chart layout margins to have wider left / right margins be default
+ Changed a sub-pixel black stroke, to a single pixel light gray - it just feels better ;-)
+ Removed fail on check-style in the build, I don't think we are ready for that yet!
+ Added a `dev` grunt task that builds then watches.