Added check for proxy bypass in HTTPConnectionWithTimeout

[jamescasbon]

This allows the connection to pick up no_proxy from the environment.

[codecov]

Codecov Report

Merging #127 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #127   +/-   ##
=======================================
  Coverage   73.57%   73.57%           
=======================================
  Files           8        8           
  Lines        2547     2547           
=======================================
  Hits         1874     1874           
  Misses        673      673

Impacted Files	Coverage Δ
python3/httplib2/__init__.py	83.36% <100%> (ø)	⬆️

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[temoto]

Thank you. Looks useful. Likely need same addition in all 4 combinations of python{2,3} {http,https}connection. And test.