Make template json extraction work

[jkomoros]

The json modifier for template extraction currently doens't work for JSON that has sub-objects

For example, changing the test json modifier full text multi-line to :

{
	"a": 1,
	"b":[
		2,
		3
	],
	"c": {
		"a": true
	}
}

Fails, because of the sub-object. The normal way of doing this is to use recursive match patterns, which arent' supported in javascript. This makes the whole "extract JSON" using the current Regex-based template matching pipeline not viable...

The only fix I see is to change the whole template extraction pipeline to not rely on regexes (or rather, to have a higher-level construct that might use regexes for pieces, but for json extraction doesn't)

Originally captured in #17.