Now with have proper exit codes for elasticsearch plugin manager (see #3463), we can add a silent mode to plugin manager.
```sh
bin/plugin --install karmi/elasticsearch-paramedic --silent
```
Closes#3628.
When installing a plugin, we use:
```sh
bin/plugin --install groupid/artifactid/version
```
But when removing the plugin, we only support:
```sh
bin/plugin --remove dirname
```
where `dirname` is the directory name of the plugin under `/plugins` dir.
Closes#3421.
David Pilato
Clinton Gormley