Clean up developer quickstart

[ssteinbach]

• formatting was confusing the table of contents. This should look nice
  now.
• Also add syntax highlighting for code examples

[codecov-commenter]

Codecov Report

Merging #717 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #717   +/-   ##
=======================================
  Coverage   81.88%   81.88%           
=======================================
  Files          72       72           
  Lines        2755     2755           
=======================================
  Hits         2256     2256           
  Misses        499      499           

Flag	Coverage Δ
#py27	81.86% <ø> (ø)
#py36	81.86% <ø> (ø)
#py37	81.86% <ø> (?)

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