Gulp: build our own bootstrap js only using the needed modules.

At this point we only use tooltip and dropdown code, but we could use
tabs or carousels in the future. Just add them to the toUglify list.

gulpfile.js

@@ -30,6 +30,10 @@ var destination = {
     js: 'pillar/web/static/assets/js',
 }
 
+var source = {
+    bootstrap: 'node_modules/bootstrap/',
+    popper: 'node_modules/popper.js/'
+}
 
 /* CSS */
 gulp.task('styles', function() {
@@ -101,6 +105,29 @@ gulp.task('scripts_concat_markdown', function() {
 });
 
 
+// Combine all needed Bootstrap JavaScript into a single file.
+gulp.task('scripts_concat_bootstrap', function() {
+
+    toUglify = [
+        source.popper    + 'dist/umd/popper.min.js',
+        source.bootstrap + 'js/dist/index.js',
+        source.bootstrap + 'js/dist/util.js',
+        source.bootstrap + 'js/dist/tooltip.js',
+        source.bootstrap + 'js/dist/dropdown.js',
+    ];
+
+    gulp.src(toUglify)
+        .pipe(gulpif(enabled.failCheck, plumber()))
+        .pipe(gulpif(enabled.maps, sourcemaps.init()))
+        .pipe(concat("bootstrap.min.js"))
+        .pipe(gulpif(enabled.uglify, uglify()))
+        .pipe(gulpif(enabled.maps, sourcemaps.write(".")))
+        .pipe(gulpif(enabled.chmod, chmod(644)))
+        .pipe(gulp.dest(destination.js))
+        .pipe(gulpif(argv.livereload, livereload()));
+});
+
+
 // While developing, run 'gulp watch'
 gulp.task('watch',function() {
     // Only listen for live reloads if ran with --livereload
@@ -138,4 +165,5 @@ gulp.task('default', tasks.concat([
     'scripts',
     'scripts_concat_tutti',
     'scripts_concat_markdown',
+    'scripts_concat_bootstrap',
 ]));