Fmt, accessor support, and null return.

[kgryte]

• Adjusts format in accordance with the style guide; e.g., tab: 4 spaces, variable declarations, brackets and spaces, etc.
• Adds accessor support.
• Creates options object.
• Adds tests for accessor and options.
• Returns null if provided an empty array.
  • Note: a bug exists in compute-median for empty arrays.
• Fixes README and documentation due to copy & paste.
• Updates dev dependencies to match most recent generator.

[coveralls]

Coverage remained the same at 100.0% when pulling d662bbb on develop into 1e3d127 on master.