Import accumulo-project bom to manage dep versions

The current pom.xml tracks specific version numbers for dependencies that are also used in accumulo.

Instead of maintaining specific versions, the pom could be updated to import the accumulo-project bom and use the dep versions based on the top-level `accumulo.version` that is specified.

If the need arises for a specific version then that could be added explicitly, but doing this would reduce the maintenance burden on accumulo-proxy.