Add a nested option on handler config definition

[wpottier]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Tests pass?	yes
Fixed tickets
License	MIT
Doc PR

Marked nested handlers with not be pushed to the logger handler array.
This options may be usefull when using custom handler (as service type handlers) which rely on a sub handler defined in the monolog-bundle configuration.
Marking this subhandler as nested avoid monolog to directly call it.

Sample Usage

monolog:
    handlers:
        foo:
            type: service
            id: my_site.custom_log_handler
        bar:
            type:  stream
            path:  "%kernel.logs_dir%/%kernel.environment%-bar.log"
            level: debug
            nested: true

services:
    my_site.custom_log_handler:
        class: AppBundle\Logger\CustomHandler
        arguments:
            - "@monolog.handler.bar"

[wpottier]

May i've missed something or this PR didn't interested you?

[Seldaek]

No it looks good to me, I just missed it :)

[wpottier]

no problem. thanks a lot for your work !