[WIP] Add metric name pass/drop filter

[titilambert]

As discuss #707, I made this PR to add metric ( measurement ) name pass/drop filter.
Specs was:

1. Rename pass/drop to field_pass/field_drop (but keep legacy support)
2. Add metric_pass/metric_drop for dropping by metric names
3. Also make this consistent in output plugins. I believe output plugins currently pass/drop by metric name (I don't think we need to implement field_pass/field_drop for them yet)
4. Keep it all glob matching for now....if we need regex we can implement as separate arg or add a prefix to indicate regex

1. : OK
2. : OK
3. : I'm not sure to understand :/
4. : OK

@sparrc if you re OK with the implementation, I will add some tests.

[sparrc]

yes, thanks @titilambert, as to (3) I don't think there is anything to do so don't worry about that.

You'll also need to change the documentation to match these new names.

[titilambert]

@sparrc tests and doc added !