Update naming for better mailing list announcement

By now, when we release the plugin, users can be confused about version naming.

For example, email title could be:

```
[ANN] Japanese (kuromoji) Analysis plugin for elasticsearch 1.8.0 released
```

We prefer to have that form:

```
[ANN] Elasticsearch Japanese (kuromoji) Analysis plugin 1.8.0 released
```

Thanks to @spinscale to reporting this.