Split between processes and load monitoring

[psaiz]

Hi @poolski ,

Thanks for the module. I've added a pull request to add a couple of configuration attributes

• The first one is to decouple the 'load' and the 'processes' monitoring. In some of my machines, I wanted to have only the fist one.
• The second one is to pass extra configuration to the metricbeat. I'm using this to pass the 'filesystem.ignore_types' (see [1]). I thought it would be better to create a generic parameter than to call it filesystem filter, which would help only for this particular use case.

Could you please take a look at it?

Thanks,
pablo

[1] https://www.elastic.co/guide/en/beats/metricbeat/5.6/metricbeat-metricset-system-filesystem.html#_filtering