Log a message if a rule cannot be found

[HamletDRC]

Assuming that you have written all your rule config in a file called "tslint.json" then I would like to see a console error if one of the referenced rules cannot be found.

For example, if I define "no-unused-whatever" and that rule cannot be found, then I want to see something on the console.

It looks like you just need to add a console.log message in the ruleLoader.ts::findRule() function. Right above return undefined

[jkillian]

This will be handled by #953. Right now it's going to throw an error - do you think just a log message would be better (see #953 (comment))

[adidahiya]

Fix is now available in v3.4.0-dev.1