Refactor to Node.js heavy environment

[mapsam]

This PR turns node-mapnik-bench into a node-centric set of scripts with some added bin commands we can use. Some major changes:

• bin commands bench and benchall used for looping through testcases
• refactored testcases structure, allows for a smaller footprint but more information about the files
• no need for map.xml files or setup.sh files any longer with the usage of mapnik-omnivore and tilelive-omnivore XML generation on the fly
• default to recording information to JSON, including a time step for every part of the puzzle
• some updates to the visual output, specifically highlighting the fastest benchmark

TODO

• [x] download script for all files located on AWS

cc @springmeyer

[springmeyer]

@mapsam - awesome. Now that this is landed, can you schedule a few handoff/knowledge share sessions so others are familiar with how to run things if you are away? How about you hit @artemp and @GretaCB?

[mapsam]

I would ❤️ nothing more than a knowledge share.

[GretaCB]

ooooooo, yes please!