Add the configuration parameters to give users the option to turn on/off...

... auto-fix feature.

This pull request will add 3 additional azkaban configs:
project.validators.fix.prompt controls whether to show the auto-fix related UI
project.validators.fix.lable controls the content of the auto-fix label
project.validators.fix.link sets the link which contains the detailed information about the auto-fix feature.
This checkbox shows up gigantic in my browser:
![giantcheckbox](https://cloud.githubusercontent.com/assets/544734/5290899/7e5a2096-7b00-11e4-9814-c2aaea7ebe13.png)
Can we make it more ordinary-sized?