Add Boxplot Chart Helper

[ethanwithnoe]

-Edited chart_helper.rb to include a box_plot helper
-Automatically scales data to fit the size of the svg

[GeorgeBerdovskiy]

Review

Tested using the data below, and the result looks fantastic! Great work 👏

[
  {
    value: 1
  },
  {
    value: 100
  },
  {
    value: 125
  },
  {
    value: 150
  },
  {
    value: 155
  },
  {
    value: 160
  }
]

Future Tasks

• Add axis with ticks
• Add styling support (preferably adapting existing style configurations)
• Add support for several data sets on one axis
• Display custom error when user tries using dataset with only one data point