renamed grunt 'base' option to 'root' (#1660)

* Allow slides to be served away from revealjs server location

The previous 'base' option conflicts with Grunt's 'base' option.
Changing it to 'root' avoids this. Further, updating to a newer Grunt
allows multiple parameters to be used. therefore `grunt serve --root="."
--root="pathtomyslides"` allows you to keep your slide content separate
from JS/CSS and such

* Live reload for relocated base

* Updated packages to match origin/dev

* Updated packages to match origin/dev

* Ensure root is an array

Gruntfile.js

 /* global module:false */
 module.exports = function(grunt) {
 	var port = grunt.option('port') || 8000;
-	var base = grunt.option('base') || '.';
+	var root = grunt.option('root') || '.';
+
+	if (!Array.isArray(root)) root = [root];
 
 	// Project configuration
 	grunt.initConfig({
@@ -69,6 +71,7 @@ module.exports = function(grunt) {
 				curly: false,
 				eqeqeq: true,
 				immed: true,
+				esnext: true,
 				latedef: true,
 				newcap: true,
 				noarg: true,
@@ -93,11 +96,12 @@ module.exports = function(grunt) {
 			server: {
 				options: {
 					port: port,
-					base: base,
+					base: root,
 					livereload: true,
 					open: true
 				}
-			}
+			},
+
 		},
 
 		zip: {
@@ -126,10 +130,10 @@ module.exports = function(grunt) {
 				tasks: 'css-core'
 			},
 			html: {
-				files: [ '*.html']
+				files: root.map(path => path + '/*.html')
 			},
 			markdown: {
-				files: [ '*.md' ]
+				files: root.map(path => path + '/*.md')
 			},
 			options: {
 				livereload: true

package.json

@@ -28,7 +28,7 @@
     "socket.io": "^1.4.8"
   },
   "devDependencies": {
-    "grunt": "~0.4.5",
+    "grunt": "~1.0.1",
     "grunt-autoprefixer": "~3.0.3",
     "grunt-contrib-connect": "~0.11.2",
     "grunt-contrib-cssmin": "~0.14.0",