Obfuscate password in output logs

Should not show passwords in any output message. Maybe create an annotation to make it ease to reuse.

For example, when we call the Fluo config command:
```shell
[root@edc0f9c776a5 conf]# fluo config -a test
fluo.accumulo.instance = test
fluo.accumulo.password = pass123
fluo.accumulo.user = root
fluo.dfs.root = hdfs://hadoop01:9000/fluo
fluo.accumulo.zookeepers = 10.10.5.10
fluo.accumulo.table = ${fluo.connection.application.name}
```