old_contents: import gulp from 'gulp'
  var shell = require('gulp-shell')
  
  
  gulp.task('mockCore', shell.task([
    'node ./utils/mockBlockstackCoreApi.js'
  ]))
  
new_contents: import gulp from 'gulp'
  var shell = require('gulp-shell')
  
  
  gulp.task('mockCore', shell.task([
    'node ./utils/mockBlockstackCoreApi.js 8889 blockstack'
  ]))
  
subject: use blockstack executable in PATH