Windows Slaves plugin failed to install due to mismatching artifact and group id.

When updating the list of available plugins in the update center, I receive:

```
Jul 20, 2014 10:46:54 PM hudson.model.UpdateSite$Plugin getNeededDependencies
WARNING: Could not find dependency windows-slaves-plugin of multi-slave-config-plugin
```

Installing the multi slave conrfig plugin, I then get: 

```
Jul 20, 2014 10:47:48 PM jenkins.InitReactorRunner$1 onTaskFailed
SEVERE: Failed Loading plugin multi-slave-config-plugin
java.io.IOException: Dependency windows-slaves-plugin (1.0) doesn't exist
	at hudson.PluginWrapper.resolvePluginDependencies(PluginWrapper.java:488)
	at hudson.PluginManager$2$1$1.run(PluginManager.java:356)
	at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:169)
	at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282)
	at jenkins.model.Jenkins$7.runTask(Jenkins.java:899)
	at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:210)
	at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
	at java.lang.Thread.run(Thread.java:662)
```

These code changes successfully download the windows slaves plugin and remove the errors.