[WIP] Spockish diff reporting

Provide Spock like diff reporting such as:
```
assert(foo === bar);
       |   |   |
       |   |   "abcdff"
       |   false
       "abcdef"

foo : abcd(e)f
bar : abcd(f)f
```
Starting with [jsondiffpatch](https://github.com/benjamine/jsondiffpatch) in this time.

TODO
----------
* [x] Searching for nice diff library
* [x] detect BinaryExpression left/right
* [ ] Dealing with Literal
* [ ] Labels and alignments
* [ ] Object / Array diff
* [ ] Refactor