npm run examples

[aashish24]

Currently to run examples, we need to run grunt (I don't know any other way). It would be nice to have npm run examples or something similar.

Here is the output of list on npm run.

[chaudhary@einstein src.git (geojson-combine-features)]$ npm run -l
Lifecycle scripts included in geojs:
  test
    karma start karma-cov.conf.js --single-run
  start
    karma start karma.conf.js

available via `npm run-script`:
  build
    webpack --config webpack.config.js && webpack --config external.config.js
  lint
    eslint --cache src Gruntfile.js tests
  ci
    karma start karma-cov.conf.js --single-run --browsers PhantomJS
  codecov
    cat lcov/*/lcov.info | codecov

[manthey]

This was added in PR #580.