Update hexagon-based icons

[colebemis]

I updated all the hexagon-based icons to use "perfect" hexagons.

Adds:

• hexagon icon (closes Icon Request: Node.js #372)
• codesandbox icon (closes Icon Request: Codesandbox #480)

Updates:

• box icon
• package icon

[codecov]

Codecov Report

Merging #567 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #567   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           5      5           
  Lines          34     34           
  Branches        3      3           
=====================================
  Hits           34     34

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[csandman]

@colebemis Not sure if you were aware but some of the strokes for the codesandbox icon are sticking out of the sides. Its not super noticeable but when you make the icon larger it catches the eye.

Just messed around with it a little bit, this can be fixed by setting the caps on the lines that are overlapping to none!

EDIT

I see now why my solution would not work, the build process applies the linecaps to the svg itself and it is not set on the individual strokes themselves. I am not sure how you should fix this but it is still something that should be addressed.