Update README for 0.15.4

Author: jchambers

README.md

@@ -25,11 +25,11 @@ If you use [Maven](http://maven.apache.org/), you can add Pushy to your project
 <dependency>
     <groupId>com.eatthepath</groupId>
     <artifactId>pushy</artifactId>
-    <version>0.15.3</version>
+    <version>0.15.4</version>
 </dependency>
 ```
 
-If you don't use Maven (or something else that understands Maven dependencies, like Gradle), you can [download Pushy as a `.jar` file](https://github.com/jchambers/pushy/releases/download/pushy-0.15.3/pushy-0.15.3.jar) and add it to your project directly. You'll also need to make sure you have Pushy's runtime dependencies on your classpath. They are:
+If you don't use Maven (or something else that understands Maven dependencies, like Gradle), you can [download Pushy as a `.jar` file](https://github.com/jchambers/pushy/releases/download/pushy-0.15.4/pushy-0.15.4.jar) and add it to your project directly. You'll also need to make sure you have Pushy's runtime dependencies on your classpath. They are:
 
 - [netty 4.1.104](http://netty.io/)
 - [slf4j 1.7](http://www.slf4j.org/) (and possibly an SLF4J binding, as described in the [logging](#logging) section below)
@@ -245,4 +245,4 @@ Callers may also provide a [`MockApnsServerListener`](https://pushy-apns.org/api
 
 Pushy is available under the [MIT License](https://github.com/jchambers/pushy/blob/master/LICENSE.md).
 
-The current version of Pushy is 0.15.3. It's fully functional and widely used in production environments, but the public API may change significantly before a 1.0 release.
+The current version of Pushy is 0.15.4. It's fully functional and widely used in production environments, but the public API may change significantly before a 1.0 release.