Copy all directories when setting up coverageEnv

[area]

The exception is node_modules, which must have copyNodeModules
set to true in .solcover.js in order to be included.

Fixes #39. I'm not sure what you want to see in terms of #43, though.

EDIT: I seem to have clobbered a load of trailing spaces in this PR too. Maybe it's best to just bin this PR 😛 .

[codecov-io]

Codecov Report

Merging #44 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #44   +/-   ##
=======================================
  Coverage   97.56%   97.56%           
=======================================
  Files           6        6           
  Lines         329      329           
  Branches       78       78           
=======================================
  Hits          321      321           
  Misses          8        8

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[cgewecke]

@area This is good. I think this should go in. The only thing that occurs to me is that there might be a couple other folder's we could habitually exclude - coverage and possibly build. Not sure they make much of difference to setup speed though so not v. important.