Scjson support

PR ready.

Assigned #230 to Jake because there is a bug on scion-core. Otherwise that test will pass.

Currently 156 tests are passing, 53 from W3C.
Closing 8 issues: 5 errors, 3 fails.

Closes #221
Closes #222
Closes #223
Closes #224
Closes #225
Closes #226 
Closes #227 
Closes #228 

Why are you cloning the node on transitions, but not on `if` or `elseif`? Why are they handled differently?

It looks like `validateJavascriptCondition` would pass boolean false back to `checkAction` as the second argument `overrideNode`, which would be `false` and would fail the test on L52, and not update the node.

Do we have any tests for illegal expressions on `if` and `elseif`? If not, please create some tests and verify that this is not an issue.