Use gulp-sourcemaps to generate a sourcemap

Chrome gets very confused by the sourceMappingURL from swagger-client.js. Use
gulp-sourcemaps to generate our own sourcemap which it is happier with (and
means that the other bits of swagger-ui.js are also correctly sourcemapped).

gulpfile.js

@@ -14,6 +14,8 @@ var header = require('gulp-header');
 var order = require('gulp-order');
 var jshint = require('gulp-jshint');
 var pkg = require('./package.json');
+var sourcemaps = require('gulp-sourcemaps');
+
 
 var banner = ['/**',
   ' * <%= pkg.name %> - <%= pkg.description %>',
@@ -58,10 +60,12 @@ function _dist() {
         .src(['./src/main/template/templates.js'])
         .on('error', log)
     )
+    .pipe(sourcemaps.init({loadMaps: true}))
     .pipe(order(['scripts.js', 'templates.js']))
     .pipe(concat('swagger-ui.js'))
     .pipe(wrap('(function(){<%= contents %>}).call(this);'))
     .pipe(header(banner, { pkg: pkg }))
+    .pipe(sourcemaps.write())
     .pipe(gulp.dest('./dist'))
     .pipe(uglify())
     .on('error', log)