run -f as the default

[guybedford]

This avoids the annoying message about left-over temporary build files on previous ncc run calls, and just always attempts to remove these files on ncc run.

This also avoids the need for the PR #258.

[codecov-io]

Codecov Report

Merging #265 into master will increase coverage by 0.16%.
The diff coverage is 50%.

@@            Coverage Diff            @@
##           master    #265      +/-   ##
=========================================
+ Coverage   74.23%   74.4%   +0.16%     
=========================================
  Files          17      17              
  Lines         885     883       -2     
=========================================
  Hits          657     657              
+ Misses        228     226       -2

Impacted Files	Coverage Δ
src/cli.js	60.38% <50%> (+0.77%)	⬆️

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[adamelliotfields]

Just pulled it down - working great with Nodemon so far.

Thanks @guybedford and @rauchg for the quick patch. I hope to contribute more in the future!