[maven] update maven-assembly-plugin to 2.5.5

```xml
<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-assembly-plugin</artifactId>
 <version>2.5.5</version>
</plugin>
```

## Release Notes - Maven Assembly Plugin - Version 2.5.5

* Bug
   - [MASSEMBLY-767] - Schema missing from the web site
   - [MASSEMBLY-768] - JarInputStream unable to find  manifest
created by version 2.5.4
   - [MASSEMBLY-769] - ZIP fileMode permissions not properly set with
dependencySet and unpackOptions

pom.xml

@@ -507,7 +507,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-assembly-plugin</artifactId>
-                    <version>2.5.4</version>
+                    <version>2.5.5</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>