Escape single quotes in printf to neurodocker_specs.json

[tclose]

Single quotes in the Dockerfile need to be escaped before using printf to save them to file

[tclose]

Hi @kaczmarj, any chance you could take a look at this as it is blocking the release of my package on PyPI? Thanks!

[kaczmarj]

@tclose - thanks for the ping. quotes have always given me trouble... let's wait until the CI passes and then i'll merge

[codecov]

Codecov Report

Merging #443 (33b5bb0) into master (664965c) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #443      +/-   ##
==========================================
+ Coverage   88.57%   88.58%   +0.01%     
==========================================
  Files          11       11              
  Lines        1015     1016       +1     
==========================================
+ Hits          899      900       +1     
  Misses        116      116              

Impacted Files	Coverage Δ
neurodocker/reproenv/renderers.py	93.36% <100.00%> (+0.01%)	⬆️

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