Rename cloudtrace package to org.apache.accumulo.cloudtrace

This is the last remaining package that does not begin org.apache.accumulo. There is a question as to whether we should do this in 1.4.0 or not. However, if we make a release first and add org.apache.accumulo later, we will have to change the name/artifactId cloudtrace as well. (I suspect the 1.3.5 release with this artifactId doesn't count because we haven't put it into a maven repository yet.)