Support for processors per handler.

[jessmchung]

@rantonmattei @mortaliorchard Please review.

This enables users to specify processors on the handler level (which gets run after logger-level specified processors are run). Elaborating on the README's sample usage for configuration yml file, for git_processor would be:

formatters:
    dashed:
        class: Monolog\Formatter\LineFormatter
        format: "%datetime%-%channel%.%level_name% - %message%\n"
handlers:
    console:
        class: Monolog\Handler\StreamHandler
        level: DEBUG
        formatter: dashed
        stream: php://stdout
    info_file_handler:
        class: Monolog\Handler\StreamHandler
        level: INFO
        formatter: dashed
        stream: ./example_info.log
        processors: [git_processor]
processors:
    web_processor:
        class: Monolog\Processor\WebProcessor
   git_processor:
       class: Monolog\Processor\GitProcessor
loggers:
    myLogger:
        handlers: [console, info_file_handler]
        processors: [web_processor]

[rantonmattei]

In your sample Yaml, the key would be processors, but no worries I will update the ReadMe once this is out.

[rantonmattei]

Looks good to me. I'm trying to see where the code coverage decreased but coveralls does not cooperate...

[jessmchung]

there was a typo here before 'formatter' instead of 'processors'...

[rantonmattei]

👍

[rantonmattei]

Looks good!