Generated json from json-reporter is malformed.

[Locitao]

Version 0.25.0.

Currently the json generated by the reporter looks like the following:

{
	"file": "src\main\java\com\saa\sample_app\base\SomeClass.kt",
	"errors": [
		{
			"line": 23,
			"column": 63,
			"message": "Unused import",
			"rule": "no-unused-imports"
		}
	]
}

As you can see, the slashes in the file name are not properly escaped. Presumably this is an error in JsonReporter

I don't have much experience with Kotlin yet, but I'll see about getting a merge request going soon.

[shyiko]

0.25.1 released 🎈