[Rockstor Devel Feature] Add Eslint over js files

[MFlyer]

No description provided.

[MFlyer]

@schakrava @phillxnet & @priyaganti do you agree on this? :)

[MFlyer]

Adding django Pipeline ref for js files order

PIPELINE = {
    'DISABLE_WRAPPER': True,
    'JS_COMPRESSOR': None,
    'CSS_COMPRESSOR': None,
    'TEMPLATE_FUNC': 'Handlebars.compile',
    'JAVASCRIPT': {
        'storageadmin': {
            'source_filenames': (
                'storageadmin/js/license.js',
                'storageadmin/js/templates/**/*.jst',
                'storageadmin/js/templates/**/**/*.jst',
                'storageadmin/js/socket_listen.js',
                'storageadmin/js/rockstor.js',
                'storageadmin/js/rockstor_widgets.js',
                'storageadmin/js/rockstor_logger.js',
                'storageadmin/js/paginated_collection.js',
                'storageadmin/js/router.js',
                'storageadmin/js/graph.js',
                'storageadmin/js/d3.slider2.js',
                'storageadmin/js/models/models.js',
                'storageadmin/js/views/common/*.js',
                'storageadmin/js/views/*.js',
                'storageadmin/js/views/pool/**/*.js',
                'storageadmin/js/views/dashboard/*.js',
                ),
            'output_filename': 'storageadmin/js/storageadmin.js'
            },
        }
}

[MFlyer]

To @schakrava :
eslint itself need info about our pipeline order, so thinking to have it all via gulp.
gulp.js has eslint plugin and..flake8 too 😄
Having this working can be useful for everyone contributing to Rockstor

Mirko