staging_ and source_ prefixed kwargs
raven basics
Merge branch '4590-logging' into 3700-sentry

Conflicts:
	pylytics/library/main.py
extra metadata
clarified frame extraction
removed redundancy
Merge pull request #75 from onefinestay/3700-sentry

Sentry integration
Merge branch '4590-logging' into 4590-logging-updated-docs
modified sentry_dsn to be uppercase