Fix default config and remove default file transport

[benoitvidis]

Description

• Fix default configuration, which was not injecting the proper format
• Remove the file transport by default, which possibly would cause disk space exhaustion risks
• Add License headers to prepare SonarCube integration
• All transports now accept all possible options (excepting functions for obvious reasons).

Related issue

• The default config is not in the right format #16

[benoitvidis]

Same output format as previous default can be set using

{
  level: 'error',
  json: false,
  filename: 'kuzzle.log',
  addDate: true,
  timestamp: false
}

[AnthonySendra]

Why do we also need "kuzzle-common-object" inside dependencies?

[benoitvidis]

You're right. At the minimum it can be moved to dev-dependencies and maybe totally removed.

Putting the PR in wip in the meantime