Change JGroups dependency scope to "compile"

Our current JGroups dependency has the scope provided. While working with the deprecated Infinispan configuration API, this worked fine as JGroups was not needed.

However, after removing the deprecated usages of the ISPN configuration API, this became a problem because Infinispan now requires JGroups when loading its classes.

Since our clustering support is provided as part of the default (modeshape-jcr) distribution, we should change the scope of the JGroups dependency to compile and make sure we don't package JGroups in any of our AS7 kits.