Replace enableLogging util with injectable Logger class

instead of relying on a function (enableLogging) that depends on a kite being an EventEmitter instance, create a new KiteLogger class and allow logger option to be passed while creating a kite:

const { Logger, Kite } = require('kite.js')
const { DebugLevel } = require('kite.js/lib/constants')
const Kite = new Kite({
  name: 'foo',
  logger: new Logger({
    name: 'foo',
    level: DebugLevel.INFO,
    handlers: {
      error: (...args) => sendToPaperTrail('error', ...args),
      warn: (...args) => sendToPaperTrail('warn', ...args),
      info: (...args) => sendToPaperTrail('info', ...args),
    }
  })
})

a logger will use console.error, console.warn, console.info as its handlers if any of them is not being passed

const logger = new Logger({name: 'foo'})
logger.critical('message is here, hello world')
// => [foo] CRITICAL      message is here, hello world

a logger will expose 6 methods in which the passed handlers are being used:
- logger.critical(...args): void -> handlers.error
- logger.error(...args): void -> handlers.error
- logger.warning(...args): void -> handlers.warn
- logger.notice(...args): void -> handlers.info
- logger.info(...args): void -> handlers.info
- logger.debug(...args): void -> handlers.info
a logger will accept a level option while it's being created which will be used to decide when one of the methods are gonna produce logs (each method has its own DebugLevel associated with it)
- These are the defined DebugLevels available:
```
export const DebugLevel = {
  CRITICAL: 0,
  ERROR: 1,
  WARNING: 2,
  NOTICE: 3,
  INFO: 4,
  DEBUG: 5,
}
```
- This will allow each exposed method to work since all debug levels are lower than DebugLevel.DEBUG which is 0:
```
const logger = new Logger({
  name: 'foo',
  level: DebugLevel.DEBUG
})

logger.debug('Hello world - debug') // DebugLevel.DEBUG == 5
logger.warn('Hello world - warn') // DebugLevel.WARNING == 2
logger.critical('Hello world - critical') // DebugLevel.CRITICAL == 0
// => [kite] DEBUG      Hello world - debug
// => [kite] WARNING    Hello world - warning
// => [kite] CRITICAL   Hello world - critical
```
- But this will only work for critical as only the DebugLevel.CRITICAL is lower or equal to 0.
```
const logger = new Logger({
name: 'foo',
level: DebugLevel.CRITICAL
})
```
logger.debug('Hello world - debug') // DebugLevel.DEBUG == 5 logger.warn('Hello world - warn') // DebugLevel.WARNING == 2 logger.critical('Hello world - critical') // DebugLevel.CRITICAL == 0 // => [kite] CRITICAL Hello world - critical

koding / kite.js

Replace enableLogging util with injectable Logger class #46