Adds syntax highlighting to README.md.

Author: ream88

README.md

@@ -11,7 +11,7 @@ You will also need the 'Apple Worldwide Developer Relations Certification
 Authority' certificate and to conver the `.p12` files into `.pem` files.  You
 can do both using the `node-passbook prepare-keys` command:
 
-```
+```sh
 node-passbook prepare-keys -p keys
 ```
 
@@ -23,7 +23,7 @@ This is the same directory into which you placet the `.p12` files.
 Start with a template.  A template has all the common data fields that will be
 shared between your passes, and also defines the keys to use for signing it.
 
-```
+```js
 var createTemplate = require("passbook");
 
 var template = createTemplate("coupon", {
@@ -38,7 +38,7 @@ second optional argument has any fields you want to set on the template.
 
 You can access template fields directly, or from chained accessor methods, e.g:
 
-```
+```js
 template.fields.passTypeIdentifier = "pass.com.example.passbook";
 
 console.log(template.passTypeIdentifier());
@@ -58,7 +58,7 @@ Optional fields that you can set on the template (or pass): `backgroundColor`,
 In addition, you need to tell the template where to find the key files and where
 to load images from:
 
-```
+```js
 template.keys("/etc/passbook/keys", "secret");
 template.loadImagesFrom("images");
 ```
@@ -71,7 +71,7 @@ you may want to specify them once in the template.
 
 To create a new pass from a template:
 
-```
+```js
 var pass = template.createPass({
   serialNumber:  "123456",
   description:   "20% off"
@@ -81,7 +81,7 @@ var pass = template.createPass({
 Just like template, you can access pass fields directly, or from chained
 accessor methods, e.g:
 
-```
+```js
 pass.fields.serialNumber = "12345";
 console.log(pass.serialNumber());
 pass.serialNumber("12345").
@@ -95,7 +95,7 @@ sigh.
 To make it easier, you can use methods like `add`, `get` and `remove` that
 will do the logical thing.  For example, to add a primary field:
 
-```
+```js
 pass.primaryFields.add("date", "Date", "Nov 1");
 pass.primaryFields.add({ key: "time", label: "Time", value: "10:00AM");
 ```
@@ -104,21 +104,21 @@ You can also call `add` with an array of triplets or array of objects.
 
 To get one or all fields:
 
-```
+```js
 var dateField = pass.primaryFields.get("date");
 var allFields = pass.primaryFields.all();
 ```
 
 To remove one or all fields:
 
-```
+```js
 pass.primaryFields.remove("date");
 pass.primaryFields.clear();
 ```
 
 Adding images to a pass is the same as adding images to a template:
 
-```
+```js
 pass.images.icon = iconFilename;
 pass.icon(iconFilename);
 pass.loadImagesFrom("images");
@@ -134,7 +134,7 @@ and a buffer to its callback.
 
 To generate a file:
 
-```
+```js
 var file = fs.createWriteStream("mypass.pkpass");
 pass.on("error", function(error) {
   console.error(error);
@@ -151,7 +151,7 @@ You can pipe to any writeable stream.  When working with HTTP, the `render`
 method will set the content type, pipe to the HTTP response, and make use of a
 callback (if supplied).
 
-```
+```js
 server.get("/mypass", function(request, response) {
   pass.render(response, function(error) {
     if (error)