Padding in function of the maximum level length at the Transport level.

[mathieumg]

This is an attempt to address #352.

• Transport.levelPadLength is set directly on the Transport instance, if you would rather I make a setter (Transport.prototype.setLevelPadLength) I have no problem with that, but I didn't see any setters so I didn't create one.
• I updated the provided Transports to use this, and it is somewhat backwards compatible with third-party Transports in the sense that they won't break or crash, but will act as if Logger.options.padLevels was ignored.
• It seems that the tests do not strictly validate the raw output of the log calls, but are rather provided a mean to validate the message content. Hence, I did not write any test.

Let me know if there is anything to modify or if you want to discuss the approach!

Thank you

[indexzero]

Thank you for your contribution. Given the stylistic nature of this change we are going to reject your pull-request. This will be possible soon (and much simpler) via custom formatters.