Require "java7" for CentOS/RHEL 6's sake.

Regrettably, OpenJDK7 (aka java-1.7.0-openjdk) on RHEL and CentOS 6 does not provide "java", ostensibly because it's still considered a technology preview. With that in mind, I'd suggest changing the dependency to be on "java7" rather than "java" so that the packaged RPM can run on CentOS or RHEL 6.