Add enable-setting to all output plugins

[urso]

No description provided.

[monicasarbu]

Shall we also update thefull configuration files of the Beats to contain enable even if it's not needed?

[urso]

Not sure. For me the enable-config mostly makes sense in conjunction with #1985 and #1986, as this will allow to disable modules e.g. from command line.

But having it named full-config, maybe it makes sense to add enable.

[tsg]

I think it should be in the full configs, as we said the full configs contain all the non-deprecated options and they can be used as a reference.

[monicasarbu]

As you already added the enable option, I would say to use it in the full -config as it's easier to just change the value of enable instead of commenting in/out an output.

[monicasarbu]

+1 enable/disable one output in the command line.

[urso]

makes sense. will add enable to full config.

[andrewkroh]

LGTM

[ruflin]

@urso there is one issue with this PR. Metricbeat uses enabled, you used enable. We should be consistent here.