Avoid fixed paths for assets

[avdv]

In our project, we need to relocate the /assets path to somewhere else because we're dealing with assets as our main model. So, the /assets/<id> is a route used for managing our assets, not loading auxiliary static files.

That's why we relocated the /assets in the Brocfile.js to another place:

var app = new EmberApp({
    vendorFiles: {
        'handlebars.js': null
    },
    outputPaths: {
        app: {
            html: 'index.html',
            css: {
                'grid': '/static-assets/overboot.css',
                'app': '/static-assets/app.css'
            },
            js: '/static-assets/app.js'
        },
        vendor: {
            css: '/static-assets/vendor.css',
            js: '/static-assets/vendor.js'
        },
        testSupport: {
            css: '/static-assets/test-support.css',
            js: {
                testSupport: '/static-assets/test-support.js',
                testLoader: '/static-assets/test-loader.js'
            }
        }
    }
});

Unfortunately, ember-cli-blanket has the path hard-coded and does not use the app.config.outputPaths settings and the build fails with:

Merge error: file static-assets/test-loader.js exists in /src/adam/tmp/funnel-output_path-Co6s3qzY.tmp and /src/adam/tmp/funnel-output_path-YOwdW5CO.tmp
Pass option { overwrite: true } to mergeTrees in order to have the latter file win.

For the same reason, installation using ember install ember-cli-blanket fails silently because it does not find the '<script src="assets/' + this.project.config().modulePrefix + '.js"></script>' line in tests/index.html nor the '<link rel="stylesheet" href="assets/test-support.css">'.