Add integration support for rails with auto-reload feature

Auto replace rails logger with log4r

_To enable log4r integration_

``` ruby
# enable log4r integration
config.log4r.enabled = true
# maximum action handling time to log with level INFO, default: 500ms.
# config.log4r.action_mht = 500# auto-reload log4r configuration file from config/log4r.yaml (or config/log4r-production.yaml in production environment)
# config.log4r.auto_reload = true
```

_Example log4r configuraion_

``` yaml
# default log4r configuration for rails development environment.
log4r_config:
  loggers:
    - name          : 'rails'
      level         : INFO
      additive      : false
      trace         : true
      outputters    : 
      - console

    - name          : 'rails::db'
      level         : DEBUG
      additive      : false
      trace         : false
      outputters    : 
      - console
      
    - name          : 'rails::controllers'
      level         : DEBUG
      additive      : false
      trace         : false
      outputters    : 
      - console
      
    - name          : 'rails::params'
      level         : INFO
      additive      : false
      trace         : false
      outputters    : 
      - console

    - name          : 'rails::models'
      level         : DEBUG
      additive      : false
      trace         : false
      outputters    : 
      - console

    - name          : 'rails::cache'
      level         : DEBUG
      additive      : false
      trace         : false
      outputters    : 
      - console

    - name          : 'rails::mailers'
      level         : DEBUG
      additive      : false
      trace         : false
      outputters    : 
      - console

  # define all outputters (incl. formatters)
  outputters:
  - type: StdoutOutputter
    name: console
    formatter:
      date_pattern: '%H:%M:%S'
      pattern     : '%d %l: %m'
      type        : PatternFormatter
```