remove additional use of cStringIO

[graingert]

Contributor Checklist:

• [ ] I have updated the release notes at docs/source/NEWS.rst
• [ ] I have updated the automated tests.
• [ ] All tests pass on your local dev environment. See CONTRIBUTING.rst.

looks like all these bin files need coverage - I'll move them to console_scripts shortly

[codecov[bot]]

Codecov Report

Merging #204 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #204   +/-   ##
=======================================
  Coverage   93.85%   93.85%           
=======================================
  Files          73       73           
  Lines       10278    10278           
  Branches     1022     1022           
=======================================
  Hits         9646     9646           
  Misses        514      514           
  Partials      118      118           

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