Fix issue with mvn-install target in build.xml.

There is a problem with the mvn-install target in build.xml. In the current code in master branch, when I run "ant mvn-install", I see the following error: "build.xml:499: java.lang.ClassCastException: org.apache.tools.ant.Project cannot be cast to org.apache.maven.artifact.ant.Pom"

This is because the pom id is set to be "spymemcached" on line 498, whereas the code below looks for ${name} which is "AmazonElastiCacheClusterClient". Similar issue is on line 506.

This patch is tested in both mac and linux.