Path constraints in json output

[zachwax101]

Would be great to have the whole end state in some nice json format, when using --extended-json-output. Especially the path, the constraints that led to the counterexample

{
"Stack": ["0xc54446db"],
"Balance: "balance_04",
"Path": ["ULE(0x4, some_paramater)", ...]
... other attribtues...
}