Update README.md (#149)

* Add version badge to README.md

It can be useful to compare `version.rb` with the version on Rubygems to
see if the gem is up to date. Having a badge on the README saves a step.

* Fixes doc links (they were all 404s).

* Use more helpful signup link

Author: sfcgeorge

README.md

@@ -1,8 +1,8 @@
 # Gem for Pusher Channels
 
-This Gem provides a Ruby interface to [the Pusher HTTP API for Pusher Channels](https://pusher.com/docs/rest_api).
+This Gem provides a Ruby interface to [the Pusher HTTP API for Pusher Channels](https://pusher.com/docs/channels/library_auth_reference/rest-api).
 
-[![Build Status](https://secure.travis-ci.org/pusher/pusher-http-ruby.svg?branch=master)](http://travis-ci.org/pusher/pusher-http-ruby)
+[![Build Status](https://secure.travis-ci.org/pusher/pusher-http-ruby.svg?branch=master)](http://travis-ci.org/pusher/pusher-http-ruby) [![Gem Version](https://badge.fury.io/rb/pusher.svg)](https://badge.fury.io/rb/pusher)
 
 ## Installation and Configuration
 
@@ -18,7 +18,7 @@ or install via gem
 gem install pusher
 ```
 
-After registering at <https://dashboard.pusher.com/>, configure your Channels app with the security credentials.
+After registering at [Pusher](https://dashboard.pusher.com/accounts/sign_up), configure your Channels app with the security credentials.
 
 ### Instantiating a Pusher Channels client
 
@@ -125,7 +125,7 @@ channels_client.trigger('channel', 'event', foo: 'bar')
 channels_client.trigger(['channel_1', 'channel_2'], 'event_name', foo: 'bar')
 ```
 
-An optional fourth argument may be used to send additional parameters to the API, for example to [exclude a single connection from receiving the event](http://pusher.com/docs/publisher_api_guide/publisher_excluding_recipients).
+An optional fourth argument may be used to send additional parameters to the API, for example to [exclude a single connection from receiving the event](https://pusher.com/docs/channels/server_api/excluding-event-recipients).
 
 ``` ruby
 channels_client.trigger('channel', 'event', {foo: 'bar'}, {socket_id: '123.456'})
@@ -155,7 +155,7 @@ This will continue to work, but has been replaced by `channels_client.trigger` w
 
 ### Getting information about the channels in your Pusher Channels app
 
-This gem provides methods for accessing information from the [Channels HTTP API](https://pusher.com/docs/rest_api). The documentation also shows an example of the responses from each of the API endpoints.
+This gem provides methods for accessing information from the [Channels HTTP API](https://pusher.com/docs/channels/library_auth_reference/rest-api). The documentation also shows an example of the responses from each of the API endpoints.
 
 The following methods are provided by the gem.