Client Tasks v1 / Bootstrap configurable (#8822)

* make bs4 configurable, change gutters to match zeplin\s

* correctly customize gutters

gulp/gulp-bootstrap.js

@@ -0,0 +1,36 @@
+import gulp from 'gulp';
+import fs from 'fs';
+
+// Copy Bootstrap 4 config variables from /website /node_modules so we can check
+// them into Git
+
+const BOOSTRAP_NEW_CONFIG_PATH = 'website/client/assets/scss/bootstrap_config.scss';
+const BOOTSTRAP_ORIGINAL_CONFIG_PATH = 'node_modules/bootstrap/scss/_custom.scss';
+
+// https://stackoverflow.com/a/14387791/969528
+function copyFile(source, target, cb) {
+  let cbCalled = false;
+
+  function done(err) {
+    if (!cbCalled) {
+      cb(err);
+      cbCalled = true;
+    }
+  }
+
+  let rd = fs.createReadStream(source);
+  rd.on('error', done);
+  let wr = fs.createWriteStream(target);
+  wr.on('error', done);
+  wr.on('close', () => done());
+  rd.pipe(wr);
+}
+
+gulp.task('bootstrap', (done) => {
+  // use new config
+  copyFile(
+    BOOSTRAP_NEW_CONFIG_PATH,
+    BOOTSTRAP_ORIGINAL_CONFIG_PATH,
+    done,
+  );
+});