logging: sentry sanitizer for access tokens

* Sanitizes access tokens from data sent to the sentry instance.
  (closes #2130)

* NOTE Upgrades raven to 5.0.0 due to changes in
  SanitizePasswordProcessor.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
logging: documentation update

* Includes logging documentation in main documentation.

* Fixes minor issues in logging documentation.

* Fixes some PEP257 problems.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
docs: license inclusion

* Adds license statement to documentation files.

* Fixes wrong license statement in certain docs files.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>