After this commit, one who depends on attester in his "scripts" part of
package.json, can additionally put in that file the following:
to specify the number of PhantomJS instances (instead of passing it via
command line), but as the added benefit, the actual user who npm install'ed
his package, could type:
npm config set somePackage:attesterThreads 8
to take advantage of his multi-core machine.
This setting is taken into account only if there was no
--phantomjs-instances passed from the command line when invoking attester.