LevelThermometer uses hard coded max level value

[mrfmunger]

The LevelThermometer component uses a hard coded value to determine the scale of the overall thermometer. If you change the pointsToLevels and maxLevel values in the constants file, the LevelThermometer will render incorrectly (since it's still referencing the hard coded value).

Locations where maxLevel is hard coded instead of referenced.
https://github.com/Medium/snowflake/blob/master/components/LevelThermometer.js#L32
https://github.com/Medium/snowflake/blob/master/components/PointSummaries.js#L25

Example

Updating the following values in constants.js results in a poorly formatted thermometer.

export const pointsToLevels = {
  "0": "1",
  "20": "2",
  "24": "3",
  "29": "4",
  "34": "5",
  "38": "6",
  "43": "7",
  "47": "8",
  "49": "9",
  "51": "10"
};

export const maxLevel = 52;