Add stacktrace to span

[kvas-damian]

Fixes #176

[arkaitzgarro]

Thanks for this, I will take a look as soon as possible and see if we can add some tests.

[arkaitzgarro]

Hey @kvas-damian,

I managed to make it work locally, and it shows the stacktraces on span level.

Could you fix the following:

• Move renderSource config into span block, since the code expects it to be there. And make it false by default, I'm a bit concern it may blow up some Kibana clusters with a high number of spans. Update the docs.
• Move getStacktrace to the parent method, to avoid extra loops.

[kvas-damian]

Thanks for your feedback. I'll try to apply changes today

[arkaitzgarro]

Looking good, thanks @kvas-damian !

[kvas-damian]

Unfortunately, I wasn't able to find a way to cover StacktraceExtractor... It depend on base_path() from Laravel, which cannot be run without bootstrap/app.php :(