Handle SimpleLazyObject in payloads

[rokob]

This needs some cleanup, but the basic idea is to handle SimpleLazyObject via a custom JSONEncoder subclass

Fixes #295

[brianr]

I'm wondering if we would want this same behavior for other things that aren't json serializable. Like... is there ever a case where we would want _serialize_payload to raise an error instead of returning something that's at least partially serialized / sorta useful?

[rokob]

Yeah that is a good point. Instead of throwing a TypeError, I will just put a placeholder.

[rokob]

So I should have tried to write the test first, I don't know why rollbar/lib/transforms/serializable.py does not handle this.

[rokob]

Specifically, the payload gets built here:

pyrollbar/rollbar/__init__.py

Line 687 in 487a78c

payload = _build_payload(data)

where _build_payload (https://github.com/rollbar/pyrollbar/blob/487a78c427c8021d46f2d211e34c500593bcb706/rollbar/__init__.py#L1314,L1327) calls _transform which applies the transforms to each key/value:

pyrollbar/rollbar/__init__.py

Line 1309 in 487a78c

obj = transforms.transform(obj, transform, key=key)

One of those transforms is a serializer transform which turns everything into a bare Python type, falling back to repr(x) or str(type(x)) depending on what happens. So I have no idea how an object can end up in the payload and make it past that transform to the json encoder. Unless someone removes/modifies the transforms. This is still useful as a fallback as apparently this is possible, but I can't seem to get it to happen in a test.