Fix logging bugs and update plugins (#87)

Fix logging bugs and update plugins (#87)

* Update README to refer to lib/ directory (lib/ext/ is no longer
  expected to exist by default)
* Add some color to the log output
* Rename log4j configuration file so it uses a name that is recognized
  as a properties file so log4j doesn't try to parse it as XML, this
  rename also allows it to be loaded from the CLASSPATH
* Use CLASSPATH environment instead of `-cp` option
* Set up class path to include the Accumulo lib/ directory so it doesn't
  complain about missing log4j runtime libraries (This fixes #86)
* Update pom.xml by updating ZK version, removing accumulo-tracer, and
  bumping plugin versions
* Fix shading warning due to migration of javax.activation-api to
  jakarta.activation-api