infinispan-tools fails to build with JDK 7 early access

infinispan-tools depends on com.sun.tools to compile Javadoc doclets. The dependency is only activated for Sun JDK currently. Since JDK 7, Oracle changed the vendor string from Sun Microsystems, Inc. to Oracle Corporation. Because of this change, the tools.jar is dropped from the build class path when Maven was invoked by JDK 7, resulting in the build failure.