Fix evaluated values

This is an attempt to fix an issue described in sebuilder/se-builder#163
which allows comparison of evaluated values.

Example:
```json
{
  "type": "verifyEval",
  "script": "return true;",
  "value": "true"
}
```
Before: Error: "true" does not match "true"
After: true

Maybe you'll want to have a look .. ?
The `examples/tests/full_example.json` runs fine ..

regards
~david