metadata_filter able to group multiple application logs

[edwardzhou]

Scenario:
there are several applications in an umbrella project. eg

finance_umbrella/
   apps/
       client_portal/
       client_portal_web/
       crm/
       crm_web/
       ...

in such case. we prefer to log both client_portal and client_portal_web into a single log file client_portal.log, instead of two isolated files client_portal.log client_portal_web.logs.

So we enhance metadata_filter supports array.

config :logger,
  backends: [
    {LoggerFileBackend, :client_portal},
    {LoggerFileBackend, :crm}
  ]

config :logger, :client_portal,
  path: "/path/to/client_portal.log",
  level: :info,
  metadata_filter: [application: [:client_portal, :client_portal_web]]

config :logger, :client_portal,
  path: "/path/to/crm.log",
  level: :info,
  metadata_filter: [application: [:crm, :crm_web]]

[PoohOka]

Totally agree with this option especially in umbrella project with external dependencies like Testla and multiple Phoenix apps.

[fireproofsocks]

I'll merge this, but I'm still awaiting being granted hex ownership per Issue #75
Until I have that, I can't actually publish a new version of the package.