Import accumulo-project bom to manage dep versions

[ddanielr]

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.

[ctubbsii]

For an example of this, see https://github.com/apache/accumulo-examples/blob/f09e8363add6a8364847345d713cbb954881c216/pom.xml#L44-L50